All EFI systems require oxygen sensors to read the oxygen levels in the exhaust. These vital sensors tell the computer if the engine is running rich, lean, or just right. But that is not all: All LS engines come with cat­alytic converters, which are used to burn up the exhaust gases to reduce emissions. This is a very important factor to consider that requires a bit of homework.

This Tech Tip is from the full book, SWAP LS ENGINES INTO CHEVELLES & GM A-BODIES: 1964-1972. For a comprehensive guide on this entire subject you can visit this link:

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Most states have a classic car provision that exempts older vehi­cles from emission standards and/or safety inspections, but it is imperative that you research the current laws in your state before completing your swap. Some states require the vehi­cle emissions to match the standards for the year of the engine, not the vehicle, which requires the engine to retain all original smog equipment (including the exhaust gas recir­culation [EGR] valve, air injection reaction [AIR], and catalytic convert­ers) in working order. Every state is different, and the laws are constantly being revised and changed, so it is up to you to make sure your LS swap is legal in your state.

Adding headers to an LS swap yields more power and often makes the installation easier.

Exhaust Manifolds

Stock Gen III/IV exhaust mani­folds are efficient and can help make more than 400 hp for most engines. The trick is finding a pair that fits your body; the motor mounts and engine installation typically deter­mine exhaust manifold compatibil­ity. One set of manifolds may fit one install and not fit another. Test fitting is the only way to verify fit.

These LS7 flanges differ from the classic Chevy three-bolt flange. You may need a long section of the downpipes to ensure you include the flange. Center-dump manifolds may or may not clear the A-Body chassis, depending on the adapter mounts. (Photo Courtesy General Motors)

The stock manifolds may or may not fit your application; information on stock manifold fitment is sketchy at best. Truck manifolds are usually too big to clear the firewall in most muscle cars, but that also depends on the forward placement. Swap headers are readily available and fit much better.

Stock downpipes also usually have catalytic converters. If you need to use them, it will save you some cash down the road. Upgrading to a high-flow cat frees up some horsepower; the choice is yours.

LT1 car manifolds do not fit the A-Body. The truck version may fit, but that has not been verified.

Even though factory manifolds fit a lot of applications, they don’t necessarily have the right look. These Hooker LS manifolds fit many applications and come with 2010 Camaro–type flanges for a good seal without searching for parts or gaskets. Although not pictured in an A-Body, they do fit the chassis.

A starter motor is often not considered during these projects, but it can present a clearance issue with some headers and manifolds. The stock starter (left) is small and powerful, but the new Petronix Contour version (right) is powerful and sculpted to give more clearance for exhaust. Unlike the stock starter, the Contour unit puts all the components inside the case, protecting them from heat and the elements.

Each starter is also clockable, so it can be rotated to clear obstacles, which makes it perfect for any LS swap.
Stock exhaust manifolds also need a compatible flange that can be welded to the rest of the exhaust sys­tem. Several flanges are used on stock exhaust manifolds, but not all of them are reproduced. The trick here is to make sure you include some of the stock exhaust, the section just below the flange, so that you have the right flanges for the exhaust manifolds. If the flange is not avail­able, fabrication is the only option.

Speedway Motors reproduces exhaust flanges for the LS1 and Vortec manifolds. Another source for flanges is used catalytic converters. You can’t buy a used converter, but you can buy the flanges. Most sal­vage yards will gladly cut them off and sell them to you.

Using the exhaust gasket as a pattern, you can cut a flange using a plasma cutter. An acetylene torch certainly cuts the steel, but it’s not the correct tool for this job because it also warps it to the point that it isn’t usable for an exhaust flange. Depending on your install, there are a couple of ways to cut new flanges.
The most common material for flanges is mild steel. For a good seal, material of 1/8 inch or thicker should be used. With a good basic outer dimension measured from the man­ifold or exhaust gasket, your local metal supply shop should be able to provide a plate cut to fit. Depending on the shop, they may be able to cut
out the entire part for you. Other­wise, using the basic plates, you can trace the inside of the gasket to the plate and then, using a plasma cut­ter, trim out the plate to the outside edge of the line. Any metal over­hang can cause some turbulence in the airflow, which impedes flow and reduces horsepower but does not sig­nificantly affect performance if the overhang is small.

If you do not have access to a plasma cutter, the following proce­dure allows you to remove any metal overhang. Using a drill bit, drill to the line at some point. If you are using Z06 manifolds, do this in each cor­ner. Then place the flange in a vice and use a reciprocating saw, air body saw, or hacksaw to cut out the cen­ter section. It may take a while, but it works. A plasma cutter, of course, certainly makes the quickest work of the job.

An aluminum flange looks great with stainless, chrome, or polished exhausts. Cutting alumi­num is easier than cutting steel and a good-looking set of aluminum flanges could be cut from plate alu­minum with a band saw and a scroll saw quite easily. Aluminum is softer than steel, so the aluminum flanges must be thicker than their steel counterparts. Aluminum flanges should be made from at least 1/4- or 3/8-inch plate. The cutting process is the same. Plasma torches quickly cut aluminum, so be careful. If you use the hand-cut method, alumi­num is softer, making it a little eas­ier. Also, aluminum cleans up nicely with carbide tips and a die grinder.

If your local shop is equipped with a CNC plasma or water jet, you can pay them to cut the parts for you. The cutting part is usually not very expensive, but the program writ­ing time is typically around $50 per hour. Because the flanges are simple, it shouldn’t take a shop longer than an hour. Once the program has been written, a shop can make as many as you want. If you are doing multiple swaps, you can amortize the cost to several engines.

Bridging the gap between a fac­tory manifold fitment and the per­formance of headers are Hooker cast-iron LS manifolds. These man­ifolds provide tight fitment coupled with better flow performance and they use 2010 Camaro–type flanges. The manifolds come with the flanges and use the OEM gaskets for a leak-free seal.
2014–Up Gen V LT-Series Manifolds
Currently, the factory offers two types of manifolds for the LT series:

Corvette and truck. The Vette man­ifolds do not fit the A-Body at all, not even close. The truck manifolds have been reported to fit in some applications, but I have not been able to verify that. Although the flanges are very similar to the LS’s, the bolts are in different places, so swapping LS manifolds to the LT is not feasible.

Headers

With all the challenges of mod­ifying stock manifolds, most swap­pers prefer aftermarket headers designed for engine swaps. Ground clearance is a common concern. Mid-length headers tend to fit best and offer the most ground clearance, but long-tubes certainly work for LS swaps as well. Manufacturers such as Hooker, Edelbrock, and Dynatech custom-fit headers for the most pop­ular LS swap vehicles.

Choosing headers requires care­ful measurements and research. You need to be careful: Some headers might fit your application but have the stock-style flange, putting you back in the same boat. Sure, you could chop off the stock flange and weld on a new one, but isn’t that part of the reason you are buying aftermar­ket headers? Some vehicle-specific headers fit late-model chassis and are designed for LS engines. These headers do not have the stock-style flange, making them excellent candi­dates for swap applications.
Vehicle-specific swap headers come with the universal three-bolt triangular flange that has been used for decades. This ensures that the headers easily mate to the rest of the exhaust. Kits are available for specific vehicles that include the headers and exhaust, all in one package.

Edelbrock

This conversion kit includes Edel­brock headers made of 409 stainless steel tubing with 3/8-inch-thick port and collector flanges. The collectors use graphite donut gaskets instead of the leak-prone three-bolt collector and gasket. These fit 1964–1972 GM A-Body cars including the Chevelle, Malibu, El Camino, Cutlass, 442, Skylark, Buick Special, GS350, GS455, GTO, LeMans, and Tempest. The Gen III/IV swap headers have 13⁄4-inch pri­mary tubes stepped up to 17⁄8 inches for maximum flow and power.
Edelbrock recommends using the Edelbrock LS-series engine mount kit (PN 6701) with the Edelbrock swap headers.
For those with Edelbrock E-Tec– series LS heads or Vortec Fast Burn heads, the Edelbrock swap headers (PN 65083) have the correct port flange configuration, so they are compatible with stock A-Body engine mounts.

The Edelbrock LS swap exhaust system matches with the headers and engine mounts, though the sys­tem works well with other mounts and headers. The exhaust system is constructed from 21⁄2-inch 409 stainless-steel tubing with an X-pipe assembly and includes a pair of SDT mufflers and a pair of polished stainless-steel tips. This kit fits the same vehicles as the headers.

Hooker

Hooker builds a couple of vehicle-specific LS swap headers: first-generation Camaro and Firebird and GM A-Body, in addition to its universal block hugger LS headers.
The 1966–1972 GM A-Body: These headers are built with light­weight, 18-gauge tuned-length 13⁄4-inch primaries, with 3-inch smooth-transition slip-fit-style col­lectors. This yields a leak-free fit to the rest of the exhaust. The head­ers are designed to fit tight to the chassis, giving increased ground clearance, from 1 to 3 inches, which is especially helpful for lowered vehicles.

This Tech Tip is from the full book, SWAP LS ENGINES INTO CHEVELLES & GM A-BODIES: 1964-1972. For a comprehensive guide on this entire subject you can visit this link:

LEARN MORE ABOUT THIS BOOK HERE

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The cylinder head flanges are made from 5/16-inch machined steel for a good seal. To accommodate the oxygen sensors, the headers include 3- to 21⁄2-inch slip-fit reducers with oxygen sensor bungs welded in, plus a set of extra bungs for a 3-inch exhaust system.
Hooker LS swap headers fit most manual and automatic GM transmis­sions, including the Tremec 5- and 6-speed manual transmissions. These headers fit other vehicles as well; research is required. These headers are designed to work with the Hooker LS swap adapters and crossmembers.
Hooker Block Hugger: This LS swap header design is tuned for low- and mid-range street performance from idle to 3,500 rpm. The primaries are made from 18-gauge 15⁄8-inch mild steel tubing, which is mandrel-bent and tuned by length to reduce backpressure and increase exhaust velocity. This design delivers more power and torque with crisp throttle response; the 21⁄2-inch collectors with a 3/8-inch-thick three-bolt flange make installation simple.
The head flange is machined to ensure a flat surface for a tight seal. The tight-tuck tube design is used to fit within narrow street rod frames and provides a good fit in most vehi­cles that do not have a dedicated swap header. The collectors exit par­allel with the oil pan for maximum ground clearance in lowered vehicles and are positioned to clear the starter and engine mounts.

Doug’s Headers

Specifically for A-Body cars, these full-length headers feature 17⁄8-inch primaries with a 3-inch collector made from 16-gauge steel and a V-band type of flange for easy leak-free maintenance. They are available in ceramic-coated or natu­ral finish.

2014–up Gen V LT Headers

At press time, no A-Body-specific headers are available for the LT. For the GS shown in this book, I had a set custom-made using the LS tube pattern for the A-Body with LT flanges. It is very close, but needs a little tweaking before it is perfect. With that in mind, by the time this book is on the shelf, there should be several LT-compatible options for A-Body swaps. The biggest difference is that the heads are slightly differ­ent, so the angle of the flanges must change. I have not tried any headers for trucks or Corvette applications; some mid-length or shorty-type headers may fit the A-Body.

Catalytic Converters

Your swap project must be equipped with a catalytic converter if the area or state where you license the vehicle mandates and tests vehi­cles for carbon emissions. You want to choose a catalytic converter that enhances performance yet meets emissions standards. Research on the construction of a catalytic converter will inform your decision.

The catalytic converter is another key component to the exhaust system. Although many states allow you to swap late-model engines without the hassle of emissions equipment, some states require it. You can use the stock stuff or switch to high-flow aftermarket parts. The core ceramic honeycomb is washed in the oxides and metals to make it function.

The 1969 Chevelle featured in this book uses a 90-degree elbow and a short section of tubing with a reducer to couple the MAF and air filter to the Holley throttle body. Creating your own kit with universal parts is an inexpensive way to get the job done. Locating the filter as close to the wheel well as possible yields the coolest air; the tubing length is not much of a factor as the run should be within a couple of feet of the engine in an A-Body.

The most important part is the ceramic matrix. Shaped like a honeycomb, the matrix is made predominantly of a ceramic material called cordierite. The honeycomb is created through an extrusion process in which lengths of the honeycomb shape are squeezed through a die and supported by computer-controlled jets of air that keep the honeycomb straight as it leaves the machine.

Once the ceramic honeycomb is fired and set, it receives a washcoat of various oxides combined with the precious metals that function as the actual catalyst. The washcoat is used because it evenly disperses the metals throughout all the pores of the matrix. The metals are generally mixed to best use their individual properties. Most cats in the United States use some combination of platinum, palladium, and rhodium. Outside the United States, copper has been tried, but it forms dioxin, a toxic substance with carcinogenic properties. In some places, materials such as nickel, cerium in washcoat, and manganese in cordierite are used, but each has its disadvantages.

Originally developed throughout the 1930s and 1940s for industrial smoke stacks, catalytic converters began to be developed for auto­mobiles in the 1950s by inventor Eugene Houdry. The first cats were mandated in 1975. They were of a two-way type, which combined oxy­gen with the carbon monoxide and unburned hydrocarbons to form carbon dioxide and water. As the science progressed, stricter environ­mental regulations brought about a change to three-way converters in 1981. These more advanced cats also reduce nitrogen oxide.

Catalytic converters work using a redox reaction. This means that once the catalyst is up to operating tem­perature (from 500 to 1,200 degrees Fahrenheit) both an oxidation reac­tion and reduction reaction occur simultaneously. That sounds a little complicated, but it just means that molecules are simultaneously losing and gaining electrons. These types of reactions are extremely common; photosynthesis and rust are both good examples of redox reactions.

In the first stage of the catalytic converter, the reduction stage, the goal is to remove the nitrous oxide and especially the nitric oxide, which when introduced to air quickly changes into nitrogen dioxide, which is very poisonous. The reduc­tion stage works because the nitro­gen molecule in the nitrogen oxide wants to bond much more strongly with the metals of the catalyst than it does with its oxygen molecules and the oxygen molecules would rather bond with each other, forming oxy­gen, which is the type of oxygen that we breathe.

Once the oxygen molecules break off from their nitrogen molecules, the nitrogen molecules move along the surface of the catalyst looking to make friends with another nitrogen molecule. When it finds one, they bond and become the stable, harm­less nitrogen in the atmosphere. After it becomes atmospheric nitrogen, its bond with the walls of the catalyst is weakened and the gas moves along to the second phase of the catalytic converter, oxidation.

When the gases have finished in the reduction stage of the cata­lytic converter, and all the nitrogen oxides have been eliminated, we are left with atmospheric nitrogen, atmospheric oxygen, carbon diox­ide, carbon monoxide, water, and unburned fuel.

The oxidation stage of the cat­alytic converter uses platinum and palladium, which want to bond with the various oxides. The oxygen mol­ecules bond with the surface of the catalyst and break up and eventually find carbon monoxide molecules to bond with, creating carbon dioxide. The carbon dioxide bond is stronger than the bond with the catalyst and moves through the matrix, allowing the process to begin again. While this is happening, some of the freed up oxygen molecules begin to bond with the unburned fuel (hydrocar­bons) and are changed to water and more carbon dioxide.

This brief overview of the design of catalytic converters is important because it shows the advancements in cat technology. The original cats were very inefficient and clogged up quickly, causing serious performance issues. Modern performance catalytic converters are designed for free flow while doing their job of cleaning exhaust gases.
Magnaflow makes high-flow cats that meet the requirements of New York and the California Air Resources Board (CARB), such as the 53006 universal 2.5-inch unit. These cats ensure the emissions of your LS or LT swap matches the necessary specs for your area.

Air Intake

To maximize performance, an LS (and any other engine for that mat­ter) needs a strong flow of dense air channeled into the engine. As you well know, when you pack more air into the combustion chamber, you pack in more fuel, and thus, you pro­duce more power. Although mufflers and exhaust systems manage exhaust gases, the air intake determines flow into the engine and it must be tai­lored to the engine and application.

Unlike the exhaust, the intake system is very simple; an air cleaner element, some tubing, and the MAF sensor are all that is required for the EFI LS and LT engine. It is possible on some swaps to simply install a cone-style air cleaner onto the throt­tle body with a built-in MAF sensor between them, but usually you need some sort of ductwork.

Large, smooth bends in the pip­ing are the hallmark of an effective intake system; the air should not make abrupt turns. Sharp bends cre­ate a vortex effect inside the tube and can drastically slow the air. Slow air means less air in the engine. Short air filter elements require the air to make fast direction changes and that siphons off potential horsepower. The best bet is to make the intake tube as straight as possible, prefera­bly grabbing the cooler air outside the engine bay.

This is not always possible, but most A-Bodies have plenty of room under the hood. For the Chevelle build in this book, a selection of components from Summit Racing and Spectre were used to match the 4-inch Holley throttle body to the 3.5-inch stock Vortec MAF sensor and cone-style air filter. A piece of 4-inch stainless steel tubing was installed between the 90-degree 4-inch silicone elbow for the throttle body. On the other side, a Spectre 4-inch to 3.5-inch stepdown was used to connect to the MAF sensor (I used a 1996 Camaro MAF) and then to the air filter.

Spectre produces vehicle-specific air intake kits for GM A-Body cars as well. These are year-specific and direct the airflow from the inner fender to the throttle body. Unlike univer­sal systems and “piece-together” intakes, these feature smooth man­drel bends that reduce air turbulence and fit like they are factory.

Written by Jefferson Bryant and republished with permission of CarTech Inc

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Fuel Pumps

You have the choice of an in-tank or externally mounted fuel pump. Most owners opt for the in-tank pump because of improved perfor­mance and reliability. In-tank pumps are more complicated to install, but tend to last longer, hold higher pressure, and are quieter. You need to detach the tank from the chassis before installing the pump and send­ing unit in it, or you could buy a complete aftermarket tank. Virtually any aftermarket EFI in-tank pump can supply the 60-psi fuel pressure required. Many builders recom­mend the Walbro 340 in-tank pump because it holds higher pressures and provides excellent performance for LS engines. Many in-tank pumps are available. The key is to buy a pump that is suited for your application. The stock F-Body fuel pump assem­bly can be purchased from GM deal­ers and used for retrofits.

This Tech Tip is From the Full Book, Swap LS Engines into Chevelles & GM A-Bodies: 1964-1972. For a comprehensive guide on this entire subject you can visit this link:

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A replacement tank is an alternative to dealing with crusty old stock send­ing units. An Aeromotive Phantom fuel pump has been installed in this Tanks replacement fuel tank. It’s a simple process to bolt in and wire up the pump.

When the pump cavitates, several problems and damage are the result. Part A shows a typical off-brand filter; the small sintered metal filter restricts flow to the pump. Part B shows the actual damage inside the pump. Cavitation grooves the aluminum and metal shavings enter the system and ruin the pump. (Photo Courtesy Aero­motive Inc.)

To simplify the fuel system, the Cor­vette regulator-filter is bypassed by adding a full-length return line under your car. The regulator-filter keeps the fuel pressure at 67 psi and redirects the unused fuel back to the tank.

I also added strips of sound deadener on top of the tank. The factory tank has rubber/asphalt strips, which do not come with the new tank. This stuff is much better anyway.

The pump is located in a recess in the center of the tank. This means that the tank fits flush just like the factory tank without any modifications to the car. A 0- to 90-ohm fuel level sender is included as well.

I recommend prewiring the pump and installing the hose fittings because once the tank has been installed, you do not have much room to do it.

Unlike the factory tank, the new unit has a detachable filler neck, so it doesn’t look stock. It also makes the tank eas­ier to install and remove. The neck does require support at the bumper, which must be fabricated.

The tank installs using the original straps in the original location.

Holley has a version of an in-tank pump. This one uses hydramat technol­ogy to eliminate the need for a baf­fle; the hydramat soaks up fuel at any angle as long as it is touching it.

When opting for an in-tank pump, you need to either buy a tank with a preinstalled EFI pump or install the pump in the existing tank. Both options can be pricey, but there are ways to keep it on the cheap as well. New tanks can cost upwards of $1,000. Companies such as Aeromo­tive build custom stainless steel gas tanks with built-in in-tank pumps. These tanks are well-built and easy to install. Each Aeromotive Phantom EFI fuel tank features a dropped sump in the top of the tank. This allows for adequate floor clearance. Each EFI tank comes with a new high-volume high-pressure fuel pump to feed the LS engine. The A-Body tank is a drop-in fit.

Ambitious builders can choose to modify the stock tank themselves. Note that the following procedure requires welding on a gas tank. Seri­ous injury or death can occur if the utmost care and preparations are not followed.

You can alter your stock tank to take an EFI fuel pump in three ways. The bargain-basement method is to take the stock sending unit assembly out of the tank, cut off a short sec­tion of feed line (about 11⁄2 inches, depending on the depth of the tank and the length of the pump), and fit the pump to the stub using fuel line and hose clamps. The import­ant thing here is to make sure the pump is mounted about 1/4 inch off the floor of the tank with a filter sock resting on the bottom of the tank. This keeps impurities out of the pump while getting the most fuel out of the tank.

The pump must be supported; a piece of steel rod can be welded to the underside of the assembly plate. The pump is then clamped to the rod so it remains stationary. This method doesn’t work for all tanks, especially shallow tanks, and you may be ham­pered by the diameter of the stock assembly. Also, the fuel-level send­ing unit may be in the way, depend­ing on the application. This method keeps the stock feed lines in place and eliminates floorpan clearance issues. One drawback is the lack of a fuel sump, which traps fuel around the pump inlet, ensuring it does not run dry. Running an in-tank pump dry is very destructive; they don’t last long when run dry.

The second option involves weld­ing on the tank. This is extremely dangerous and should not be attempted in haste or by novices. All old fuel must be removed, and the tank thoroughly rinsed, drained, and rinsed again until there is absolutely no possibility of any remaining fuel vapor. If you smell a hint of gas, do it again. To add an extra measure of safety, fill the tank with water or inert gas such as argon while the welding is being performed. If you have any doubt, seek the help of a profes­sional. Most fuel tank builders offer their services for retrofitting tanks. Employ their services if you can.

Installing a custom in-tank pump in the top of the tank often requires a recessed panel on the top. The fit­tings clear the floorpan and give you a flat surface to mount the new assembly. If you place the top sump to the side of the original, the stock sending unit can be used, simplify­ing the process. This requires a boxed section be built and welded to the top of the tank. Then a fuel-pump assembly unit is built with both wir­ing and inlet and outlet fittings. This piece should have a bar or rod on the inside portion of the tank for the pump to mount to.
Using 90-degree hose barb fit­tings is usually the easiest way to get the fuel in and out of the assembly. These fittings must be sealed tight so they do not leak. The entire assembly bolts to the sump.

In addition, by installing baffles to the inside of the tank, fuel sur­rounds the pump at all times. These should be added before the top sump is installed.
You can also weld in a sump in the bottom of the tank. This sump is placed directly below the pump, but the pump is installed in the lowered section, with the filter sock on the floor of the sump. Tanksinc. com offers an upper tank mount, complete with a fuel pump and baffle. This reduces some of the legwork in building this piece and ensures the pump always is covered with fuel.

The third option allows you to install a truly high-performance fuel pump into a stock fuel tank without welding. Aeromotive offers two ret­rofit in-tank pump kits: the Phan­tom and the A1000 Stealth. For basic street performance use, the Phantom 340 is suitable. This kit allows you to simply cut a hole in the top of the tank, drop in the pump, bolt it down, and hook up the lines. The kit comes with the seals, hardware, and a drill jig to ensure the holes are in the right place. The 340 supports up to 700-hp supercharged EFI engines, or 1,000-hp supercharged carbureted systems. That leaves plenty of room to power a stock 400 LS3. The Phan­tom system fits in just about any tank, so this is a good option that takes out the guesswork.

For more serious performance engines, the Stealth A1000 system feeds up to 1,300-hp EFI systems and 1,500 for carbureted engines. Install­ing these systems takes slightly more effort than the Phantom kit, but not much.

Inline Fuel Pumps

External or inline pumps offer a simpler installation and are usually more affordable, so you can make roadside swaps. The main gripe over inline pumps is the noise. The rel­atively quiet and smooth-running Gen III/IV engines do not drown out many external sounds, includ­ing these inline pumps. Therefore, drivers may hear the whir of the electric pump sound over the engine with a stock-style quiet exhaust. For most builders, the added noise isn’t a problem but rather an inconve­nience, but for a show car, a noisy pump might be considered a serious drawback.

The real drawback for an inline pump is that the fuel line is only pressurized after the pump, so the tank to the pump is gravity fed. Anyone who has dealt with a mod­ern high-performance external fuel pump can tell you that life is diffi­cult when you lose the siphon in the tank. Simply having the pump in the tank maintains a constant supply of fuel to prevent those hard-cornering and acceleration woes that come with a stock tank and an inline elec­tric fuel pump. Inline fuel pumps also require a more substantial return line system because of the long dis­tance between the regulator and the fuel tank. Inline pumps are also sub­ject to failure through heat. The only thing that cools the pump is the gas flowing through it.

Not all inline pumps are cre­ated equal. External pumps come in all different shapes and sizes, with most of the market consisting of low-pressure units designed for car­buretors. These pumps deliver 6 to 14 psi, and are not close to the 60 psi required to operate an LS engine. Any less than 60 psi and it leans out and does not run well, if at all. You have plenty of inline EFI pump choices. Many builders prefer the Walbro GSL 392 external pump. These pumps are well-suited for Gen III/IV engines and can supply the pressure needed.

Installing an inline pump is sim­ple, but there are a few caveats. The first is to always install a pre-filter before the pump, so the pump does not become clogged and ruined. A pre-filter is basically a screen-style fil­ter that traps the big stuff. A micron filter should be placed after the pump to catch small contaminants. Do not install a micron filter in front of the pump (between the tank and the pump) because it impedes the gravity feed and there is not enough force to push the fuel through a micron filter.

Make sure the pre-filter is large enough to free-flow the fuel. A small pre-filter restricts flow to the pump, causing cavitation, and burns up the pump. A stock-type metal canister pre-filter works great, but they are not pretty. Most aftermarket fuel pump makers have large-capacity pre-filters if you want one that looks good. Most of the aftermarket pre-filters are rebuildable as well.

Cavitation is a natural process that occurs when vapor bubbles are induced in liquid under pressure. All electric fuel pumps are susceptible to this force. Its most common cause is installer error when an inadequate fuel supply increases the suction on the inlet side. Cavitation is literally boiling the fuel through pressure. Vapor bubbles form and then split, imploding, causing a micro explo­sion. This is extremely damaging; even a few minutes of cavitation can ruin a fuel pump.

Another cause of cavitation is overheated fuel. Not running a return line (deadhead style) or attempting to plumb the return line into the feed line (not into the tank) causes hot fuel to cycle back through the pump, heating it up more. The hot­ter the fuel, the easier it is to cavitate or even vapor lock. Yes, EFI systems can vapor lock too. This is the reason a proper return system is so import­ant for EFI.

The most important aspect of any electric fuel pump is the wir­ing. It is most difficult to get solid grounds because paint, rust, and scale inhibit the ground. Always be sure to remove the paint and anything else from the ground location, so you have clean metal. Electricity requires equal grounding and positive current flow. A bad ground is just as bad as a faulty positive feed. Electric fuel pumps require a lot of current; run­ning a relay circuit from the pump trigger lead, along with 12-gauge positive and negative wires to the fuel pump, provides ample capac­ity. This ensures the pump receives the required amperage without overheating the wires. Do not run a 16-to-24-gauge primary wire to a fuel pump because it will cause a fire. All fuel pumps require at least 12-gauge power wire, with the larger pumps needing 10-gauge wire. This includes both power and ground wires.

Gen V LT-series engines are dif­ferent from the LS series, particularly in the fuel system department. All LT-series engines are direct-injection, meaning the fuel is pressurized to more than 2,000 psi and injected directly into the combustion cham­ber, much like a diesel engine. Because of this, the fuel system is dra­matically different. Instead of a basic fuel pump and regulator, the factory pump is controlled by the ECM and a fuel pump module to control the pressure.

LT-series engines use a different style of fuel feed. Instead of the standard return line, the direct-injection fuel system uses a pulse width modula­tion (PWM) controlled pump that varies the pump speed to maintain 72 psi. This little computer and sensor manages that operation.

To add the pressure sensor, I needed a fuel log. Buying one is easy, but I had some leftover fuel rail and made one. The sensor has 10-mm metric threads, and adapting that to an existing log is difficult, so this works best. First, I drilled into the center of the block until I hit the port. Next, I stepped up to the correct bit size for the threads on the adapter. I have a small -6 AN to 10-mm adapter; it is a brake fitting. Then I secured the block in a bench vise, and used a high-quality tap to cut a 9/16-inch threaded hole in the block. Use cutting fluid or lubricant to keep the tap from galling in the block. The adapter port has been finished and is ready for installation. This 3-inch-long block from Holley includes a section of universal fuel rail for direct-port EFI kits.

The PWM signal is highly suscepti­ble to inference. To remedy that, the wires are twisted or braided. The harnesses in the GM ECM kit are not long enough to reach the back of an A-Body, so you extend their length. A minimum of 27 twists per 8 feet is required. I lightly braided mine to keep it from untwisting.

I tapped the ends for -6 O-ring fit­tings, and then installed the proper fittings and sensor with O-rings and thread sealant.

Here is the adapter fitting. It is -6 male on one side and 10-mm male on the other. These are hard to find; you have to order them online.

Under the car, I used a tube nut and sleeve to convert the 3/8-inch feed line to mate with the -6 AN fittings. This reduces the potential for leaks and AN fittings seal very well.

I mounted the fuel controller between the floorpan and transmission cross­member. This is as far back as the harness allows. The controller is weatherproof. Just make sure that the plug is flat or pointed downward; do not position the plug where water can accumulate. This mounting also limits the potential for debris damage.

I installed an Aeromotive post-filter (100-micron filtration) to the sensor block. This filters the fuel after the sensor before it gets to the engine.

I connected each line to the block and filter assembly and secured the lines with bolt-in clamps. Make sure the wires for the sensor are routed away from heat and moving objects.

A special pressure sensor in the fuel line monitors the pressure of the fuel, which is maintained at 72 psi. Rather than use a regulator, the pressure is managed through PWM control of the pump. Essentially, the ECM uses PWM to control the speed of the pump, ensuring constant full pressure with no delays. This compli­cates the fuel system for the LT-series engine swap. You can’t use just any pump; the pump has to be able to be PWM controlled. Before you pur­chase a pump, make sure it is PWM capable.

The LT system is returnless to keep the fuel temperature down; therefore, hot fuel does not return to the tank and the fuel temperature stays down. The pump requirements are 72 psi at 45 gallons per hour (gph) with the Chevrolet Performance con­trol system. Although this system is more complicated in terms of wir­ing, it does eliminate the need for a return line.
Many swappers already have an existing electronic fuel system in their vehicle. Swapping an LT into that scenario could mean buying new parts, but all is not lost. You can bypass the PWM-style pump system by using a standard electric pump with a return line and regulator set to 72 psi at 45 gph. That is fairly high for a street pump, so make sure your pump is capable of providing the required flow and pressure.

Installing the PWM controller is relatively simple, but installing the fuel pressure sensor is a bit difficult. First, you need an inline adapter with a pressure sensor port positioned at 90 degrees, or 5 to 85 degrees to the flow of fuel, according to the GM manual for the fuel controller. Because plenty of these fuel sensor adapters are avail­able, this is relatively easy.
The problem is that most of the adapters are for 1/8-inch NPT fittings, and not the 10-mm threads required for the GM sensor. Finding a 1/8-inch NPT male to 10-mm male adapter is the difficult part. What you can find easily is a -6 AN male to 10-mm adapter. To use this, you need an alu­minum fuel log or Y-block fuel split­ter and a -6 AN to 10-mm male-male adapter. This allows you to connect the sensor into the fuel system. (I made one with a leftover piece of fuel rail from another project.)
The PWM pump controller is a plug-and-play component, but the pump wiring is not. Three wires come off the pump module: yellow with a black stripe, gray, and a smaller-gauge black wire. The yellow/black wire is the ground, the gray wire is the power side, and the small black wire is the shield. If you have a GM pump with a shield pin, connect the small black wire to that pin; if you have a pump without a shield pin, leave the wire unterminated and tape it to the other wires.

Because of the nature of PWM control, you may experience elec­tromagnetic interference from other electronics in the car. To keep this from interrupting the control signal, the two main power control wires are twisted with a third shielding wire. This wire is grounded to the chassis near the pump. The Chevrolet Per­formance wiring harness comes with a certain length only; the A-Body chassis absolutely requires longer wires. To maintain the shielding, you must twist the wires a minimum of 27 twists per 8 feet of wire.

The best way to ensure that the wires are correctly twisted and don’t unravel is to braid the three wires together. It does not need to be a tight braid, rather a consistent loose braid, wrapping the wires around every 3 inches or so. Do not use crimp connectors for these wires; make sure you solder them well and use shrink tubing.

Most EFI engines (except for 2014–up Gen V LT-series engines) require return lines. This can some­times be confusing because Gen III/ IV engines use a single-line fuel rail. The 1997–1998 Corvettes and 1998– 2002 F-Body LS1s used a dual-line fuel rail. In 1999, the Corvette LS1 went to a single-line rail, using a

The stock fuel rails use a snap-on clip fitting. I used these fittings because they convert the GM clip-on style to -6 AN fittings for a clean look.

The adapter pops on and the clip keeps it secured in place. This is very convenient and makes servicing the fuel system easier because the clips can be a pain to remove.

LS engines need a return line, and it also connects using the push-on fittings. Most 1970–1972 A-Body cars have a factory hard line that runs back to the tank (5/16 inch), so you can simply connect to that line. If you don’t have one, you need to run one. It can be a regular fuel line because the return side is low pressure.

It is a good idea to pressure test the fuel system before firing up the engine. This helps you find any leaks and address them before the situa­tion becomes dangerous. LS engines require 60 psi to operate.

filter regulator near the fuel tank and running a short return line back to the tank. This configuration is much simpler and requires only a single line run the length of the vehicle. Many builders prefer to run two lines the distance of the vehicle with the dual-line fuel rails.
The benefit of running a full-length return system is cooler fuel. The fuel does not sit in the lines, heating up from the pressure. Instead, a constant flow of fuel is running through the lines, ensuring cooler fuel and, therefore, more power. This, of course, requires two sets of fuel lines: a 3/8-inch line for the feed and a 5/16-inch line for the return. Some muscle cars and trucks came with return-style mechanical pump fuel systems, but these are not the norm for older vehicles; most were deadhead systems, meaning that the fuel simply stops at the pump until it is sent on to the engine.

If you choose the simple one-line route, you need the 1999-up Corvette filter regulator. This unit has two lines (an input and an output): one on the side for the fuel tank, and one on the other side for the output, which goes to the engine. It is a one-line system to the engine, and there is a short return line from the regulator/filter to the tank. This pre-set regulator pro­vides the correct 60 psi to the engine, which pressurizes the entire fuel line while pumping the excess fuel back to the tank. This is typically mounted as close to the tank as possible to min­imize the length of feed and return lines to the tank.

For a dual-line system with the pump in the tank, you need a filter between the pump and the fuel rails. It is best to filter the fuel as soon as possible to keep the fuel lines as clean as possible.

Installing new lines is not dif­ficult, but it can be nerve racking. You have three ways to accomplish this task: install pre-bent hard lines, bend new hard lines, or run braided hose,. Using pre-bent hard lines is the simplest method if the vehicle has the fuel tank in the stock loca­tion. Pre-bent lines such as those from Classic Tube and Tube Tech are patterned after the original lines in the car and should fit just like the originals. That is not to say that com­promises and tweaks are not needed along the way.

Bending and installing custom lines most effectively transports fuel the length of the vehicle, but it is much easier said than done. This is a chal­lenging task that requires some metal­working skills, and therefore the task is frustrating at best for the novice. Tube manufacturers such as Classic Tube offer custom bending services. Using coat hangers or other wire, a pattern is bent by hand and sent to the maker. The maker bends a set of hard lines to your specifications and ships it to you. This ensures quality bends with proper flare where you want them (without kinks) and without the aggravation of doing it yourself.

The third option is to use flex­ible hose for the long runs. This works, but you should use braided hose rather than plain rubber hose to protect from road debris damage. The chance of road debris snagging a long braided fuel line is much higher than with a hard line. Rubber lines are not the best option, either. Rub­ber lines dry out and crack much faster than hard lines corrode, so you must replace the rubber lines eventually.

Written by Jefferson Bryant and republished with permission of CarTech Inc

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The LS motor mount uses a four-bolt mount that bolts to the side of the engine block. This is not directly compatible with the standard three-bolt Chevy small-block mount. The most common solution for this change is converting the LS engine to the more usual early-style three-bolt engine mounts.

The original Chevy Gen I small-block from 1955 featured the three-bolt motor mount configuration, and the same motor mount pattern continued in production through the second-generation small-block, the LT1 and LT4. However, these engines are not to be confused with the new-generation 2014–up LT1 Gen V series. (Yes, General Motors reuses its nomenclature and it can be very confusing.)

Numerous companies make adapter plates to convert the LS mount to accept a Chevy small-block three-bolt mount. With so many adapters (hundreds of different brands are available), deciding which to use is the tough part.

This tech tip is from the full book, SWAP LS ENGINES INTO CHEVELLES & GM A- BODIES: 1964-1972.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

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When compared to the Chevy Gen I/II small-block, the stock LS engine motor mounts are located farther back toward the bellhousing. If a motor mount is bolted to the frame using these holes, in most vehicles the engine sits too far forward. This increases the nose weight of the car, causing instability.

Some adapter mounts are for specific applications, such as the Holley mounts for GM A-Body cars. In addition, universal adapters are available with offset mount locations, such as 1.25 inch forward and .5 inch up, to better facilitate engine placement for chassis and body clearance. Dirty Dingo offers adjustable adapter plates, so you can get the positioning just right for your application.

Bolting the adapters to the engine is simple: four socket head bolts and you are done. Make sure you use some anti-seize compound to prevent galling of the different metals.

Simple adapter plates are a common solution for many LS swaps’ engine mounts. These plates from Hooker are made of billet aluminum. They bolt to the Gen III/IV four-bolt engine mount pad and allow a three-bolt GM motor mount to bolt on.

Not all adapters are the same. This kit from ATS flips the Chevy small-block mounts upside down to set the engine lower in the chassis. These are designed to fit the first-generation Camaro and the GM A-Body.

Simply bolting the adapter plate to the engine block provides mounting provisions for the old-style Chevy small-block three-bolt engine mount. This allows the LS-series engine to essentially drop right into the chassis without much effort.

For yet another alternative, American Touring Specialties (ATS) offers a set of LS adapter plates that feature an early-style motor mount in an upside-down configuration. ATS offers this arrangement so the engine can sit lower in the car and farther back toward the firewall, for better stability and a lower center of gravity. With these ATS mounts, an LS engine can be swapped into most any GM A-Body.

Depending on the motor mount, certain interference issues may occur, most commonly, oil pan to crossmember and ground clearance, passenger-side valve cover to air conditioning compressor, and transmission bellhousing to transmission tunnel clearance.

Some adapters, such as these TransDapt mounts, require a lock nut on the back side of the plate. The external webbing makes it a bit of a pain to install the lock nuts, but these nuts are recommended to add extra security.

Opinions vary as to which adapter style is the best fit for 1964– 1972 A-Body platforms. The reality is that it depends on your engine, transmission, and component combination. This time frame in GM’s history was the beginning of using corporate parts throughout the GM brands.

Before 1964, GM nameplates Cadillac, Chevy, Buick, and Oldsmobile manufactured and installed parts unique to their respective models; as a result, only a few components were shared across brands. In most cases, the chassis platform shared the frame or unibody structure, but very little else. In 1964 this changed, and suddenly GM brands were using “corporate” parts that interchanged between platforms, starting with suspension components and transmissions.

Engines, however, were still brand-specific. Although this does create a bit of a headache, the nice thing for 1968–1972 A-Body builders is that all the frames are drilled for every engine stand. You can easily bolt a Chevelle engine stand into a Buick, Oldsmobile, or Pontiac frame.

Converting a 1968–1972 BOP (Buick, Olds, Pontiac) to work with the standard LS conversion mounts is handled one of two ways: convert to Chevy small-block frame stands or use LS-specific frame stands.

Once the locking nut is on the backside, you tighten the bolt in the plate (which is also threaded) and then tighten the lock nut. If your adapter plates require nuts, you can use a box wrench with a tap on one side to hold the nut in place while you install it.

The early 1964–1967 A-Body cars are more difficult because these were not designed to accept all engine makes. A Buick used Buick mounts, a GTO/LeMans used Pontiac mounts, and so forth. A couple of aftermarket solutions do not require welding: Hooker (Holley) and BRP Hot Rods adapter mounts. They use existing holes in the frame to adapt the chassis to accept an LS engine mount. The Hooker mounts use the fourth-gen Camaro LS motor mounts, and the BRP mounts use a proprietary polyurethane mount. Conversion mounts that adapt non-Chevrolet A-Body frames to accept a Chevy small-block mount are readily available through companies such as Original Parts Group.

When adapter manufacturers talk about “stock location,” it is important to recognize that this refers to the original engine-to-transmission mating surface plane. LS engines are 1 inch shorter than a traditional Chevy small-block. Therefore, they do not have offset cylinders, and this means that the rear of the block is shorter than the Gen I block. Adapters that position an LS in the “stock location” place the transmission mating surface in the same location it would be if a Gen I Chevy small-block were installed in the vehicle.

Chevy Adapter Mounts for the A-Body

Most adapter mounts are designed to work with the standard Chevy small-block three-bolt engine mount. For the A-Body, three different versions of motor mounts are offered: clamshell tall/narrow (early style), and short/wide.

Clamshell Mounts
The clamshell type is more common on later GM vehicles, but can be found on 1964–1972s. These use a stamped steel pod that bolts to the engine with a steel and rubber mount that bolts to the frame. These can be used with most adapter mounts.

Tall/narrow, short/wide, and clamshell are the three main types of motor mount that have been used for the typical Chevy small-block frame stands. The clamshells are completely different from the other types. The tall/narrow mounts (left) are used for 350s and big-blocks. The short/wide mounts (right) are used on 307 cars. They both bolt to the engine, but wreak havoc on your engine position and install.

Tall/Narrow Mounts
These are the most common in Chevrolet A-Bodies. The tall/narrow distinction is confusing, however, as the frame pad is called short/ narrow. Tall/narrow refers to the engine-mounted component. These Chevy small-block mounts from a small-block 350 were adapted to the big-block 396/454 engines in Chevrolet A-Body cars. The center of the engine mounts measures 23 ⁄8 inches between the mounting ears and 23 ⁄26 inches from the center of the mounting bolt to the top of the engine mount pad. On the frame stand, the mounting pad measurements are 23 ⁄8 inches wide and 15 ⁄8 inches tall (crossmember to pad). The GM part numbers for these frame stands are 3980711 for left-hands, and 3980712 for right-hands. These frame stands are readily available in the aftermarket as reproductions.

There is about a 1/4-inch difference in overall height between the tall/narrow (left) and the short/wide (right) versions, but it’s not enough to allow some other components to fit. In addition, the narrow mounts don’t sit down on wide 307 frame stands.

Most LS engine adapters position the engine closer to the radiator, which is fine, because most of them do not run mechanical fans.

Short/Wide Mounts
Chevrolet used a different set of frame stands for the 307 than the 350 engine when installed in A-Body cars. The 307 frame stands are 1/2 inch taller than frame stands for the 350 engine. The width of the pad (where the two mounts come together) is also different. The 307 mounts are wider and measure 25 ⁄8 inches on both the frame stand and the engine block mount. However, the block mount measures 13 ⁄4 inch tall and therefore is shorter than the 350 version.

These are the most commonly sold mounts at the parts store, so it pays to know the difference.

The type of mount you need depends on your vehicle and the accessory drive and oil pan you use. That being said, the best solution is to use the 350 version. These raise the engine a little higher than the 307, which provides better clearance for the oil pan and steering linkage. In most cases, you still need to raise the engine a little more to clear the steering linkage. About 1/2 inch usually works, depending on your oil pan and the angle of the engine/ transmission. Most adapter plates require the 350 version.

Most A-Body cars have an interference issue with the inner tie-rod ends. The Mast oil pan for A-Body swaps has the best clearance, but you may need to raise the engine to get adequate clearance. The Hooker kit (shown) and similar kits have complementary parts that work as a complete system, and include mounts, pan, and headers.

Even with the right parts, some inner tie-rods are simply larger than others, which could result in light scrubbing, such as this on the bottom of the pan. This occurs at the extreme end of the turn radius

This tech tip is from the full book, SWAP LS ENGINES INTO CHEVELLES & GM A- BODIES: 1964-1972.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

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With the mounts on the block, the engine can be lowered into the car for a test fit. It is a good idea to test fit your engine before finalizing the details.

Energy Suspension’s correct tall/narrow mounts provide adequate clearance using the Trans-dapt adapters and Mast oil pan. The inner tie-rods just barely touch at full lock.

Hooker offers another LS swap solution for A-Body vehicles, particularly for non-Chevrolet brands that don’t have factory Chevy small-block frame stands. Instead of searching for Chevy small-block stands, you can use these pieces along with a fourth-generation Camaro LS motor mount to place the engine in the correct position. These are available in both “stock” position and in the 2-inch-forward position.

For the 1969 Chevelle project featured in this book, the 350 mounts were used with a set of Energy Suspension 31117G motor mounts and a Mast oil pan. The driver-side inner tie-rod cleared, but the passenger’s side hit the pan. I raised the engine with an additional spacer block between the engine and the mount, which allowed everything to clear. The Energy Suspension mounts come with one spacer; I used two.

LS Frame Stands

Using an aftermarket stand is an alternative to sourcing original Chevy small-block frame stands. Several versions are available with the most common being the Hooker (Holley Performance) mounts. These fabricated steel mounts bolt to the 1968– 1972 frames in the factory-drilled forward Chevy small-block position. The stands are designed to fit Gen-IV F-Body (1998–2002 Camaro) block mounts. The two versions of this mount are stock engine position and forward position.

Under the hood of the 1971 Buick GS lies this 400-hp Buick 350. Although the engine is in great shape, it is time for something new. The latest generation of GM horsepower, the LT1, will do nicely.

Even though the Buick shares most of the chassis components with the rest of the A-Body platform, the frame stands are not compatible. Only Chevy small-block mounts work for LS swap adapters, so the Chevy small-block mounts need to be installed. The Buick mounts shown here are set back way too far and too wide.

Accessing the bolts is tricky; you need a combination of wrenches and sockets to get to each of the nuts and bolts through access holes in the frame. The bolts pass through from the backside of the frame member.

Position A, or the forward position, is designed to reduce floorpan modifications for T56 6-speed transmissions and allows bolt-in installation of Turbo-Hydramatic 350, Turbo-Hydramatic 400, 2004R, 700R4, and 4L60/70 automatic transmissions. Position B, or stock engine position for a Gen I Chevy small-block, allows a TH350, TH400, or 2004R to mount to the engine using the stock crossmember without floor modifications. These mounts require extension floorpan mods with late-model transmissions and a custom transmission crossmember.

BRP offers a replacement mount that uses its proprietary Muscle Rods engine block mounts. This complete system includes a transmission crossmember and is designed to fit with Hedman Muscle Rod LS swap headers as well.

Chevelle small-block 350 stands replaced the Buick stands and, indeed, it makes a difference. The Chevy 307 stands are different from the big-block stands. For the install, I bolted them in place using the forward holes in the frame. All 1968– 1972 A-Body frames are drilled for all types of frame stands. I also used new Grade-8 bolts.

Earlier A-Body cars use a variety of adapters. Chevrolet models are easy, as Chevy small-block adapters are the standard. If you are swapping into a BOP A-Body car, you need to swap out the original mount for the Chevy small-block-type mounts. Although the non-Chevrolet mounts look as if they are the same or similar, they have different dimensions that are not compatible for completing a swap.

Another issue is that BOP frame stands are often in a different position than Chevrolet versions, similar to the later 1968–1972 frames. The most common solution is to use the 1964–1967 Chevelle 350 mounts for these early A-Body swaps.

Unlike the 1968–1972 models, the 1967-and-earlier frames use a single bolt pattern for all GM makes, three bolts in a triangular pattern. The frame stands themselves are different. This means that you must install Chevy small-block engine stands into the frame. Some swappers weld the engine stands to the frame, which demands a serious commitment to the placement of the engine. You must be 100-percent sure that the location is correct.

These Dirty Dingo mounts allow up to 2 inches of lateral movement. Adjustable motor mounts give you latitude to adjust the position of the engine and, therefore, flexibility to fit the exhaust, steering, air conditioning system, brake booster, and other underhood components. They are very popular because they offer more options for engine placement than other designs.

Adjustable motor mounts, with their many components, are more complicated to install, however. The slider (black piece) must be removed before the adapters are placed onto the block.

A spacer plate comes with the adapters to locate the mounts for the proper height in the chassis. Leave these out and you will not be able to install the bolts into the frame stands.

If your block is aluminum, you need to use anti-seize on the supplied Grade-8 bolts to prevent the threads from galling.

You mount sliding plates back onto the adapters using the installed studs. The final torqueing of the nuts and bolts is done after the position of the engine is set.

Here you can see the bare adapter. The “P” with an arrow dictates the side and front of the engine.

The bolts have hex heads; be careful not to strip the hex head when torqueing the bolts.

With the stands in place, set the new LT1 in the chassis, allowing you to check the fit for the oil pan and components.

Fortunately, this is not necessary. The 1964–1967 Chevy small-block frame stands are readily available as reproductions.

Hooker frame stands provide an alternative to converting to the Chevy small-block mounts. The stock location in 1964–1967 cars presents a major component fitment problem similar to the issue in the later A-Body. Often there is not enough clearance between inner tie-rods and the oil pan, but also the transmission and A/C compressor fitment are an issue with the stock setback. Hooker 1964–1967 frame stands provide a viable solution because you can position the engine 1 inch forward from its stock location. When used in the complete Hooker LS swap system, all component clearance and fitment issues are alleviated.

BRP also makes kits for the 1964– 1967 GM A-Body cars. Similar to kits for later vehicles, these bolt to the chassis and use either the Gen IV Camaro (Holley) or proprietary (BRP) motor mounts on the engine.

The 2014–up Gen V LT-series engines are similar to Gen III/IV blocks, but not enough to make them a simple drop-in replacement. At the current time, the aftermarket does not provide a full selection of motor mounts for the new generation of LT-series engines. There are a few options, however. The engine mounting location is the same, but the Gen V has a different bolt pattern. Dirty Dingo has sliding mounts for LT A-Body swaps that use the Chevy small-block frame stand and engine mount. The slider allows you to position the engine 2 inches forward, or aft, of its mounting position.

Written by Jefferson Bryant and republished with permission of CarTech Inc

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Regardless of the vehicle, the oil pan is often the most difficult obstacle to overcome in an engine swap. Unlike the LS platform, which has no less than 10 oil pan variations from the factory and countless aftermarket options, the Gen V LT-series engine only has four factory options, none of which are well-suited for swaps, and the aftermarket is just now offering proper solutions. As with anything, a little research and fabrication helps move things along.

From the start, you need to know that modifying an LT oil pan is a nonstarter. Unlike LS pans, the LT’s oil pickup tube is built into the pan itself; it is cast into it. This makes chopping out sections of the pan to clear obstacles not possible like it is on the LS pans. Fortunately, the aftermarket has solutions. Sorting out what works and what doesn’t depends on many variables, including the chassis setup, engine and transmission mounts, intended use for the vehicle, and the engine itself.

FACTORY OIL PANS

There are four factory pans: truck, LT1 wet-sump car, CTS-V/LT4 wet sump, and LT1/LT4 dry sump. Eventually there will be others, but these are the current GM factory options. They are all cast aluminum with integral pickup tubes and oval oil ports to the block. This means that you can’t simply cut and weld the oil pan. The factory oil pans all have a fairly large sump, which is far forward on the pan itself. This means that in most full-frame car applications, the factory pan simply will not fit. Most 2WD trucks will accept the factory car wet-sump oil pans without additional modification, but the truck pan does not fit.

Truck Pan

The truck pan is quite large. Not only is the shallow section of the pan very short, there is a sheet metal extension pan that bolts to the bottom of the main sump. It is very deep, which makes it impractical for use in car swaps. The truck pan will fit 1972-and-older trucks without modification, but 1973-and-newer trucks will require special motor mounts and heavy crossmember modifications. Oil capacity is 8 quarts.

What is certainly the most popular LT-swap engine, the L83 5.3L truck engine has a unique oil pan design, which uses a cast pan with a metal bolt-on sump. Additionally, some L83 and L86 truck engines have an air-to-oil cooler system, as shown here by the aluminum block and lines coming from the pan. It can be used or deleted.

LT1 Car Wet Sump

Found on most LTl-powered cars, the standard wet-sump oil pan is shallow, measuring just 4.75 inches from the bottom of the block. The main sump is 15 inches long and measures 4.75 inches at the back to 4.5 inches deep at the front. The shallow section is 7 inches long and tapers from 2.5 inches deep at the rearmost section to 1.5 inches at the front of the pan (front of engine). This pan will fit most trucks, but most cars will require crossmember modifications because the main sump section is too far forward to clear. Oil capacity is 7 quarts.

This Tech Tip is From the Full Book, How to Swap GM LT-Series Engines into Almost Anything. For a comprehensive guide on this entire subject you can visit this link:

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2016–2017 CTS-V/LT4 Wet Sump

This pan is very deep, making it unlikely to be suitable for most swaps. The shallow front section is 11 inches long, so it may clear some stock crossmembers, depending on the engine setback. The shallow section is 1.5 inches deep at the front, tapering to 2.5 inches at the shelf for the main sump. The 7-inch-deep sump is 12 inches long. The main issue with this pan is that it is quite deep, leaving it exposed to road debris and potential destruction. If the vehicle is lowered at all, this pan should not be considered. Oil capacity is 10 quarts.

This is the LT1 wet-sump oil pan with the water-to-oil cooler system installed. The oil cooler does not fit most chassis designs. 

The high-powered CTS-V/LT4 wet-sump oil pan is quite large. It may work in some trucks, but the pan is very deep, 7 inches at the deepest section of the sump, so it is not a good option for lowered vehicles.

LT1/4 Dry Sump

Certain vehicles and crate engines come with an optional dry-sump system. The pan for this is similar to the wet-sump car pan, but the shallow section is a little bit shorter than the wet-sump pan, making this a difficult swap for most full-frame vehicles without modifications to the crossmember. This pan has two oil drain plugs. Oil capacity is 9.8 quarts.

Modifying the crossmember to clear a factory oil pan is not complicated, and while it does require good quality fabrication, it is a fairly simple process. The key to this is taking plenty of measurements with several reference points that will not change. This allows you to place the engine without the oil pan installed, make measurements for clearance, and extrapolate the necessary notch required for your application.

AFTERMARKET OIL PANS

It took the aftermarket a few years to get going on LT-swap components, but it has finally come around and there are several LT-swap pans available. Currently, there are four oil pans available for the Gen V LT-series engine: the Holley Retro-fit (standard and drag race versions), the Moroso fabricated pan, and two pans from BRP HotRods—the High Clearance and Extended Sump. All of these pans are designed to add clearance for LT-swaps and should work for most applications. The details set them apart—as does the price. All of these pans are designed for wet-sump oiling systems.

Holley Retro-Fit Street and Drag

Holley has been at the forefront of the LS swap game for quite some time, and things are no different when it comes to the LT-series engines. Like its LS pans, the LT Retro-fit Street pan (part number 302–20) is cast aluminum, has a built-in oil filter port that matches the factory placement, and has all the other fittings seen on a factory pan.

The pan reduces the rear sump length by 5 inches, providing plenty of clearance for full-frame vehicles, and is only 1 inch deeper than the factory sump, so there is good ground clearance for lowered vehicles. 

This pan fits just about any application where an SBC or LS would clear. The shallow front section is just 1/4 inch deeper at the front than the factory wet-sump car LT pan.

This Holley swap pan fits like a dream and has all the same features as the factory pans, but this one actually fits most chassis designs. The Holley pan is the most affordable of all the currently available options at around $400.

The Drag model (part number 302–22) is the exact same oil pan, only with an added set of baffles that bolt into the pan for controlling oil slosh in extreme G situations. This is specifically designed for drag race applications. This keeps the oil in the sump surrounding the pickup where it needs to be.

At approximately $400, the Holley Retro-fit models are the cheapest solutions to the factory pan. Unless you really want to modify your frame, you can’t get a pan for less. It comes with the Holley quality that you would expect, and it looks good. It is cast aluminum, which can be polished if you are looking for a fancy oil pan, painted, powder coated, or left raw. This is a simple solution for a difficult problem.

The only potential issue with this pan is that it is cast aluminum. The only real drawback is that if it is hit hard enough, it can crack, leaving the engine without oil. Is this likely? No. Not even a little. But it could happen. The factory pan is cast aluminum as well, so this really isn’t much of a drawback. Because it is cast aluminum, adding additional fittings to the pan is more difficult.

Moroso Wet Sump

This Moroso fabricated pan (part number 20155) is made from sheet aluminum, which means that the pan is flat and square. There are no little bumps or raised sections in the middle of the flats that can cause clearance issues. This pan features a billet aluminum O-ring rail to match up to the block and a removable pickup tube. It uses Moroso’s billet oil filter adapter, so the stock location can be used for the filter; no remote filter is required like most sheet metal pans use.

The front shallow section is 1⁷∕₈ inches deep and 14½ inches long. The rear sump measures 5⁷∕₈ inches deep and 8½ inches long, so there is plenty of clearance for most crossmembers. Included with the pan is a trap door baffle and windage tray for better oil control.

The sheet metal construction makes it lightweight, and adding other fittings to the pan (such as an oil return for turbos) is easy. Because it is not cast, road debris is less likely to crack or split the pan because the sheet metal aluminum will dent rather than crack like cast aluminum.

The disadvantage is that the Moroso pan is nearly double the price of the Holley pan, so that is a big drawback. It might make up for it if a return fitting for turbo system needs to be added, but that can be done on both.

BRP HotRods High Clearance Sump

The High Clearance pan (part number 000-6490-00) is designed specifically to work with BRP’s MuscleRods swap kits. It is a fabricated sheet metal pan like the Moroso. It features the correct O-ring placement and pickup tube. It is a very good-looking oil pan, and the aluminum is easily polished. The high-clearance version is for applications that require maximum clearance, such as Tri-Five Chevys.

This is the BRP HotRods LT swap oil pan, which is a fabricated pan (welded sheet aluminum instead of cast), which is quite nice. It fits the block, has all the right ports, and is designed to work with the BRP LT swap system. 

BRP HotRods Extended Sump

If you have a front steer-style steering system, the extended sump pan (part number 000-6451-00) is suggested by BRP to gain the clearance without losing the 5-quart capacity. It has the advantage of sheet metal construction for less weight, and it fits BRP swap kits. However, these pans are very expensive to build, and that is reflected in the price, which is similar to the Moroso pan.

Regardless of which pan is chosen for a swap, it will likely need to be removed at some point. This is a bit different from every other GM engine that came before it. There is no oil pan gasket, instead General Motors used gray RTV silicone. Gray silicone is specifically used for high-torque applications where sensors and oil are present. It is important to use the gray silicone on the oil pan because it is the only defense against leaks.

Another potentially catastrophic issue with the oil pan install/removal is the oiling fitting O-rings. There are three: one on the pickup tube to the block and two on the oil filter ports that run to the external cooler or bypass cover. These have a habit of sticking to the engine block when removing the pan, so the pan will come off with these missing, and if you miss it during the process, you can lose them, which would mean a massive internal oil leak and no oil pressure. If you are replacing the pan or putting on a new O-ring but the old one is still on the block, you will have a really tough time getting it all to go back together.

Written by Jefferson Bryant and republished with permission by CarTech Inc.

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The first thing that needs to be done in a swap is physically fitting the engine into the chassis. This may require several attempts, so make sure to have a quality engine hoist, heavy chains (or better yet an adjustable load leveler), and a helper. It is much easier and safer to do this work with help. Make sure to have a level, measuring tape, and notepad for taking measurements and notes on the fitment into the chassis. If the original engine is still in the chassis, take photos and measurements for reference.

Installing an LT engine begins with engine mounts because this is the key to everything else. There are many ways to get this done, depending on the vehicle. A bolt-on adapter is the most common and by far the simplest solution.

Motor Mounts
Much like the LS platform, the LT-series engines use a four-bolt engine mount that is just forward of the block centerline where the rear two bolts split the center cylinders. A small-block Chevy (SBC) has mounting bosses on the block that sit roughly between the two front cylinders. This pushes the LT forward of where the typical SBC sits. Adapting the LT to fit where an SBC or LS rested is not much of an issue; retrofitting an LT to a platform other than that is a little more challenging, but even that is pretty simple.

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Dimensionally, the LT is about the same size as the SBC, although the back of the block is shorter than the SBC because there is no ledge for the bellhousing. Additionally, the mechanical fuel pump is at the back of the block, requiring extra clearance. Most swappers simply adapt the LT-block mounts to the commonly available SBC mounts and then go from there. With so many options for placement, it can get a bit sticky trying to figure out exactly what is needed.

The factory motor mounts are a wild departure from the standard SBC style. There is a large damper on a large three-bolt flange. Shown here is a 2014 L83 engine with truck motor mounts.

The factory LT engine mounts are wildly different from SBC-style mounts. These mounts use a large polymer bushing to dampen the engine vibrations. The bushing is bolted to the frame, as opposed to a clamshell that is secured with a single through-bolt. In some instances, the factory mounts can be used, but they are very large and require substantial fabrication to get the alignment right. Using SBC mount adapters offers more options, and they are generally easier to fabricate frame stands for.

Typical installations need the engine in the factory SBC location, which references the bell-housing mounting plane. This is 1¹∕₈ inches rearward from the factory LT mounting point, so these are known as 1¹∕₈-inch rearward adapters. This position works well in most GM vehicles but not all. The 1987 Camaro project featured in this book required setting the engine, an L83 5.3L truck LT-series engine, just 5/8 inch rearward to gain the necessary clearance for the firewall. We used adapters from Trans-Dapt, which also makes the 1¹∕₈-inch rearward adapters and 5/8-inch forward pieces for vehicles that need even more clearance.

Adapting an LT to a factory GM SBC frame stand is a balancing act. There is the firewall clearance to deal with as well as the front of the engine. The oil pan and accessories can get in the way, especially when using factory components. In most cases, the factory truck-only vacuum pump will not clear any GM muscle car frame, but it will clear on most truck chassis. Additionally, the factory AC compressor location is on the passenger’s side, down low, tight to the block. Many aftermarket adapter mounts simply will not clear the factory compressor, and the compressor does not clear the frame or crossmember in most vehicles, so you have to sort that out.

Adapter Plates
Most swappers elect to use adapter plates because they are simple and allow the use of readily available (and inexpensive) SBC mounts. There are many options for adapters from single-position adapters, which are the most common and simple, to multi-position and even sliding mounts. We have used all three types, and they have their benefits and drawbacks. The biggest issue with single-position adapters is that they are just that: one position. If you run into a clearance issue, purchase a different set that works with your project.

There are substantially fewer companies making Gen V adapters compared to LS adapters, which means fewer are available to choose from. This isn’t really a big problem, however, because those that are available are quite versatile. Brands including Trans-Dapt, ICT Billet, and Dirty Dingo have the parts needed. For those swapping LTs in the place of LS-series engines, ICT Billet even makes Gen V LT-to-LS chassis adapters.

Trans-Dapt
If basic adapters are needed, these are the ones you want. They are built from laser-cut steel and painted black, and they work. They come in three flavors: 1¹∕₈ inch rearward, 5/8 inch rearward, and 5/8 inch forward (with or without rubber or polyurethane engine mounts). We used these in the 1987 Camaro featured here. They fit well, clear all of the components, and do precisely what they are supposed to, all for less than $80 (plates and hardware only, no mounts).

The measurements reference the relative position of the engine to the factory LT position, not the mounts themselves. So, 5/8 inch rearward means the engine itself sits 5/8 inch from the LT-series mount, which is half the difference between the SBC and LT positions.

Let’s say you have a custom chassis or something that is not already fitted with GM SBC frame stands. In this case, custom mounts are needed. Trans-Dapt has you covered with the 4604 and 4605 biscuit-style mounts. Similar to the early SBC front mounts, these adapters are universal for frame rails that are 27 to 33 inches (4604) and 24 to 30 inches (4605) apart, so the tabs can be bolted or welded to the chassis, and then the LT can be simply dropped in place. This greatly simplifies the process of swapping an LT into non-GM vehicles. Just about any non-GM application can make use of these mounts for around $115.

This block adapter can use any of the three main GM motor mounts types: tall/narrow, short/wide, or the 1973–1998 clamshell style. This mount sets the engine rearward 5/8 inch, which is half the distance between an SBC bellhousing plane location and the LT plane location. The Camaro featured in this book used this measurement because the SBC position is too close to the firewall.

ICT Billet
Say that you need an LT because you already swapped an LS into your car but you want the latest and greatest in powertrain technology, or maybe your factory LS-powered car is just not up to the task anymore. Well, my friends, the geniuses at ICT Billet have the part you need: billet aluminum LS-to-LT swap adapters. These adapters relocate the LT engine to the LS position in fine style. They clear all the important components and come with the hardware to mount them.

ICT Billet also has multiposition mounts for LT swaps. This means there are three unique position options with a single adapter. All positions move the engine 0.72 inch up in the chassis, which may not work for those using the very tall truck intake, but this provides clearance for the crankshaft-to-front crossmember clearance, which is a problem in some vehicles. The three positions are set at the stock SBC position (1.125 inches back), 1.625 inches forward, and 2.25 inches forward. This measurement refers to the actual engine position.

These billet aluminum adapters from ICT Billet are drilled for multiple positions from the stock SBC position to 2.25 inches forward.

ICT Billet states that its adapters will allow the use of the factory AC compressor and vacuum pump in the 1.625-inch position with the plates trimmed to remove the factory SBC position mounting holes. Although, this may cause a clearance issue between the oil pan and steering linkage or front crossmember.

DIRTY DINGO
Another option is to purchase mounts from Dirty Dingo, which has two styles: static multiposition and sliding mounts. We used the sliding mounts on a 1971 Buick GS, and they worked very well. They allow the position of the engine to be adjusted to fit the original Buick 350 frame stands, which is something that no other mount will do.

MULTIPOSITION
Like the other multiposition mounts, these start with the factory SBC position, which refers to the bellhousing mounting plane. This is the most rearward position for the engine using these mounts. From there, the mounts move 11/16 inch forward, 1¹¹∕₁₆ inch forward, and 2¼-inch forward from the stock SBC position. These mounts do not clear the factory AC or vacuum pump. They use multiple positions drilled and tapped into a single mount, so the position of the engine can be adjusted as needed without buying new mounts.

The frame stands determine which style of motor mount is needed. This one is on the 1971 Buick GS, and it is not compatible with any of these adapters because it is a Buick frame stand. Oldsmobile and Pontiac each have their own versions, so you need to convert to Chevy stands.

For unique circumstances, the sliding mounts may be the best bet. These mounts allow the engine to be positioned in the stock SBC location, up to 2 inches forward, and anywhere in between. This means that minor adjustments can be made for specific applications, while static mounts can’t be adjusted. These mounts are quite long and a little complicated to secure, but they are worth it if you are working with nonstandard frame stands, such as Buick, Olds, and Pontiac. They do not clear the vacuum pump or AC compressor using the factory accessory drive.

These Dirty Dingo mounts were the first commercially available LT swap mounts, and they provide some options that you don’t get with other adapters. Instead of a single position or several fixed points, the adapter bolts the block, while the motor mount bolts to a second piece that slides on the block adapter. This allows you to put the engine wherever you need it. These are very large though, so they do interfere with the factory AC compressor mount.

GM TRUCK MOUNTS
Standard adapter plates work for GM two-wheel-drive (2WD) trucks with SBC frame stands, but four-wheel-drive (4WD) trucks are a much different story. The crossmember is in the way, which keeps the standard mounts from working. Dirty Dingo offers 1973–1999 Chevy truck 4×4 mounts that are adjustable from the standard SBC position up to 2.5 inches forward and an additional 1/2 inch rearward. These are made from laser-cut steel and are powder-coated black. They do not clear low-mount AC but will clear the vacuum pump.

SBC
Most adapter mounts are designed to work with the standard SBC three-bolt engine mount. For GM-chassis vehicles, there are three different versions of motor mount: tall/narrow (early style), short/wide, and clamshell. The first generation of SBC mount was a biscuit mount used on 1955–1957 GM chassis. In most cases, these chassis need to be converted to a later-style engine stand.

Clamshell
The clamshell type is more common on later GM vehicles, but they can be found on some converted 1964–1972s. The clamshell’s design uses a stamped-steel pod that bolts to the engine with a steel and rubber mount that bolts to the frame. These can be used with most adapter mounts. 

These are the common SBC-style mounts that most LT-swap adapters use. There are two versions of these mounts. The most common is the tall/narrow (left), which are used in most GM applications. On the right is the short/wide mount, which are used on GM 307 SBC applications. Determining which one is needed depends on the available frame stands.

Tall/Narrow
These are most common in Chevrolet muscle cars. However, the tall/narrow distinction is confusing because the frame pad is called short/narrow. The tall/narrow refers to the engine-mounted component. These are the SBC mounts used for 350/396/454 engines in Chevrolet vehicles. The center of the engine mounts measure 2³∕₈ inches between the mounting ears and 2³∕₂₆ inches tall (from the center of the mounting bolt to the top of the engine mount pad).

On the frame stand, the mounting pad measurements are 2³∕₈ inches wide and 1⁵∕₈ inches tall (crossmember to pad). GM part numbers for these frame stands are 3980711 for left hand and 3980712 for the right hand. These frame stands are readily available in the aftermarket as reproductions.

Short/Wide
For the Chevy 307-ci engine, General Motors used a different set of frame stands. The frame stands are taller than the 350 version by 1/2 inch. The width of the pad (where the two mounts come together) is also different; the 307 mounts are wider, measuring 2⁵∕₈ inches on both the frame stand and the engine block mount. The block mount is shorter than the 350 version, measuring 1³∕₄ inches tall. These are the most commonly sold mounts at the parts store, so it pays to know the difference.

One of the biggest issues with LT1 swaps is the water-to-oil cooler. In most applications, this simply does not clear the frame. Most GM trucks have enough clearance, but car frames do not. 

The type of mount needed depends on the vehicle, the accessory drive, and the oil pan. That being said, the best solution is to use the 350 version. These mounts raise the engine a little higher than the 307, which provides better clearance for the oil pan and steering linkage. In most cases, the engine will still need to be raised a little more to clear the steering linkage. About 1/2 inch usually works, depending on the oil pan and the angle of the engine/transmission.

If working with a non-SBC-powered GM chassis (such as a Buick, Olds, Pontiac, or Cadillac), then convert to the SBC version of frame stands. In most of these applications after 1964, the same-year SBC frame stand should fit. On pre-1964 vehicles, General Motors had not fully switched to universal frame designs, so a Buick B-Body frame is not the same as a Chevrolet B-Body. This requires modifying the chassis to either accept the SBC frame stands or building a custom stand to mount to the engine.

Written by Jefferson Bryant and republished with permission of CarTech Inc

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You have transformed a common stock F-Body into a high-performance muscle car, and as such, you need to carefully inspect and monitor the systems during first start-up. If you have installed a new crate engine with a warranty or a freshly rebuilt engine pulled from a junkyard, you need to pay particular attention to the engine when it is started for the first time. If you have installed a used engine, it has run before; it should do so reliably now and you do not have to break it in.

My 1968 Camaro is now complete and ready for first start-up. It is fitted with a Speed Tech front subframe and rear suspension and a myriad of other parts. This fade-away shot shows the MAST Motorsports LS3 beneath the hood.

This tech tip is from the full book, SWAP LS ENGINES INTO CAMAROS & FIREBIRDS: 1967-1981.

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First, you need to be alert and sharp so you can identify problems. You need to be prepared to shut the engine down immediately if a problem is discovered; you want to avoid doing any damage to it.

Be sure that all of the fluids are topped off. Make sure your oil pan is filled to capacity, which is 5 or 6 quarts. I recommend that you use actual break-in oil that contains ZDDP (such as Joe Gibbs “driven oil”). But before you actually fire up the engine, you should pre-lube it, so oil adequately coats all internal surfaces, including rocker arms, lifters, and main bearings.

If you don’t pre-lube the engine, you take a chance on damaging vital components because some areas may be starved of oil while the oil pump works up to full pressure. You invested a tremendous amount of time and money in your LS swap so you don’t want to cut corners because it could result in a fatal mistake. Goodson sells an air pressurized pre-lube tank system (PN PL-40) used with an air compressor that sends oil through the engine, but it costs $200.

Another method is to build your own pre-luber and that’s easily done. You can install a small-block Chevy oil pump in a 5-gallon plastic bucket and puncture it with an electric drill so that oil is drawn out of the bucket, routed through the engine, and returned to the bucket. Doing it this way ensures the engine is properly protected for first start-up.

Be sure to mount an oil pressure gauge on the engine so that you can verify oil pressure when you’re circulating oil through the engine.

Safety should always be paramount with any automotive project and this one is no different. Make sure the transmission is in “Park” or “Neutral” (that is, not in gear) and that the emergency brake is set. You should also chock the wheels so the car cannot roll.

Systems Checks

This section prepares you for many of the common missteps folks make when rushing into starting their car for the first time and somehow fouling it up. Worse yet is when you’ve invited everyone over for the grand unveiling. The first celebratory beers are cracked, you hear a fizzle when you turn the key, and look like a dope when you ask everyone at the party to, “just hang on . . .”

VATS

The vehicle anti-theft system (VATS) is pretty standard on most GM vehicles. This means that the key is matched to the lock cylinder; the engine does not run if they are not harmonized. The easiest fix is to have the company that reprogramed your ECM and wiring harness edit this part out of the code. If you have full power to the car but no starter engagement, you just might have a VATS problem.

Park/Neutral or Clutch Switch

The lockout for the clutch or park/neutral switch is in the wire bundle of the LS-engine ECM. If the computer doesn’t recognize that the clutch is depressed or that the car is in Park or Neutral, the computer does not send the signal to the starter of the vehicle. Double-check that this is installed properly or as a last resort (and I don’t recommend this) you can ground the wire from the ECM to fool it into believing that the switch is depressed. This is clearly a safety item and should be wired to engage this feature whenever possible.

Clutch Engagement

The LS engine typically uses hydraulics to actuate the clutch. Most, if not all, of the setups around have a fully hydraulic clutch, meaning the system uses a master and a slave cylinder. If you haven’t bled the system yet, you need to do it before you start the engine for the first time because the clutch’s default position is “engaged.” (See Chapter 7 to bleed your system effectively.)

An easy way to tell if the clutch has adequate engagement is to support the rear wheels securely on several jacks so they can spin freely. Have a helper push the clutch pedal down (disengaged) and try to turn the rear wheels with your hands. If they don’t move, you have a problem.

Oil Pressure

You should have an oil pressure gauge on your car, no debate. If you don’t, get one now! The single greatest thing that kills an engine faster than your quarter-mile times is oil starvation.  

Your setup might look like this for a while if you plan to tune it yourself. I used the tuning software that came with the Mast engine to reprogram the system after an intake swap.

Be sure to prime the system first. General Motors recommends that you fill the engine with oil and disconnect the engine control system. Then, using an oil pressure gauge, crank the engine in 10-second bursts until oil pressure is achieved. You can remove the spark plugs to help relieve pressure in the system.

When you start the car for the first time, oil pressure should be instantaneous. If you do not get any reading on your gauge within 5 to 10 seconds, shut the engine down and start diagnosing the problem. A lack of oil pressure can be many things, such as major malfunction in the oil pump. Be sure that the oil pick-up tube is matched to the oil pan before you install it in the car so you don’t have to take it apart later.

Leaks

I’ve seen it more often than not that people get a little overzealous and start pounding on things unnecessarily. I once even got a little ahead of myself and forgot to put the lower power-steering hose on the build. I finally realized it after half a quart of fluid spilled all over the floor.

It helps to make a checklist of fluids that could possibly leak and simply make a mess or be a symptom of a much larger problem. Fuel leaks are the most common followed by leaks of radiator fluid, power steering fluid, brake fluid, transmission fluid, rear end housing fluids, and engine oil.

Fuel

You need to verify that your fuel system provides between 58 to 60 psi. This can be checked via an external gauge or in my case, a fuel pressure gauge that is part of the gauge cluster in the dash. The easiest way to check this is to turn the key to the on-position, but do not engage the starter. You should hear the pump whine a little and this means it’s turned on. Keep in mind that the pump is designed to only turn on for 5 seconds before shutting off in the key-on position.

If you do not have pressure or can’t hear the pump prime, it needs to be corrected. Most often it is simply an easily corrected wiring issue. (This would be a good time to double-check your other wiring connections and make sure they are secure as well.)

When you are testing fuel pressure it’s usually a good idea to bleed the system of air. If you have AN fittings, a small crack with a wrench sometimes gets most of the air pockets out. Otherwise, the engine may need to be cranked and run for a short time to get all the air out of the system. This is a great time to double-check for leaks while the system is under pressure; you should be able to spot them rather quickly.

Nut and Bolt the Car

I cannot stress this point enough; you need to double- and sometimes triple-check your work. I highly suggest that you put the car on jack stands or up in the air and “nut and bolt” the car. This means going through the car systematically to make sure that every nut and bolt is tight and ready for service. Nothing would stink more than to find a crucial loose bolt when you’re 50 miles from home. Even Mark Stielow has said that he finds loose nuts and bolts from time to time after driving his hand-built rolling works of art.

Engine Break-In: First Firing and Test-Drive

Some people jump right in their newly built ride and take off. This may be fine for some, but I like to keep my stuff in one piece for as long as possible. The best option is to break in the engine on an engine dyno so you can control all aspects of the engine break-in. If that’s not possible and you have to break in the engine in the car I have several recommendations.

If this is your first fuel-injected engine you may be pleasantly surprised at how easily and quickly these engines start up. They self-regulate instantly. I do not recommend using the gas pedal at all while starting the engine because it can confuse the throttle position sensor; let the engine and ECM do all the work.

The engine idles relatively fast at first, roughly 800 to 1,200 rpm until it goes into “closed-loop” operation, which means that the computer has recognized that the engine is ready for normal operation. This usually means that the engine has good oil pressure, the coolant is at a safe temperature, fuel pressure is good, and there are no obvious issues with the fuel/air mixture or any sensors malfunctioning. This is a good time to monitor your gauges to make sure that they are accurate and that they are reading safe numbers for each engine statistic. If all seems well, look for leaks such as in the high-pressure power steering line. Many leaks don’t show unless the car is running.

If no leaks are detected it is time for a test drive. There are many ways to truly break in an engine and drivetrain components. The following procedure has worked well for me for many years.

First, cycle the fuel pump a few times. It’s entirely possible you have air in the system, so I suggest cracking the system open at the fuel rail to let the air bleed out.

After the start-up, it’s important to let the piston rings seat in the bores. Long gone are the days of letting the flat-tappet cams and lifters mate over time. LS engines have fixed that little problem for all of us. I recommend hitting the city streets; piston rings love a variable-RPM range during the break-in period. I also suggest keeping the RPM below 3,500 and no full-throttle accelerations. Engines also hate long constant-RPM drives right away. Several engine builders have told me that this plan should be followed for the first 500 to 1,000 miles of the engine.

After the first drive, monitor the fluid levels and top off any that need it. Lunati often recommends changing the oil after 100 miles to get rid of the initial bearing wear, then at 500 miles, and then at 1,500. It has also been recommended that for LS engines, conventional oil should be used for the break-in process as it promotes piston ring and cylinder wall seating. After the 1,500-mile oil change, you should stick to the manufacturer’s recommendations for oil change intervals.

The final step is to enjoy the car! Keep an eye on all the vitals and have fun. That’s the name of the game!

Written by Eric McClellan and Posted with Permission of CarTechBooks

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I want to remind you again that this needs to be planned out. If you do it correctly, you won’t run into any major snags. If you are going to have a problem, it will most likely be when you bolt the headers up when the engine is already between the frame rails.

This is the original exhaust that I pulled out of the 1968 Camaro test vehicle. This system would probably work pretty well but because I installed a sophisticated rear suspension the exhaust system had to be suitably rerouted. This is a custom kit from Jegs that’s compatible with my rear suspension system. Exhaust systems like this are fairly inexpensive and can be installed in less than a day. I liked the rumble, but I had to get rid of it because of size constraints.

This tech tip is from the full book, SWAP LS ENGINES INTO CAMAROS & FIREBIRDS: 1967-1981.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

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The reason that companies sell complete kits that include engine mounts, oil pans, and headers is that they are designed to work in concert. I have seen many combinations of mounts, pans, and headers that work just fine. On the other hand, I’ve seen plenty of setups with the headers hitting something they shouldn’t be hitting and that’s never a good thing.

So, once again, I feel the need to repeat that if at all possible get the engine mounts, oil pans, and headers from the same place. Why settle for “making it work” when you can just “have it work.”

Headers

Headers have come to be the defining purchase after the engine is acquired. However, the purpose of headers is to maximize exhaust flow while providing optimal scavenging. The result is the best-performing exhaust for your particular application. You should select headers for your type of driving.

In broad terms, a street engine benefits from optimized torque because the car operates at lower RPM and lower speeds. You want your F-Body to launch quickly from a stoplight and accelerate quickly. On the other hand, a road-race engine needs to produce high-RPM horsepower to be competitive because many road-race engines live at 6,000 to 9,000 rpm all day long. Therefore, you need to need to define the application of the car and common operating RPM so you can select the best set of headers.

As with other LS parts, you have many header choices, but you need to select headers that match your application and are compatible with your total engine package. Hooker, Hedman, Street & Performance, and others make LS exhaust systems for first- and second-generation F-Body swaps. You can buy the pieces separately from different manufacturers; this may entail more problem solving and fabrication work. Or you can buy a complete system for your particular F-Body. Jegs offers several Hooker Header swap kits, which include a direct-fit aluminum radiator, engine mount kit, and hooker headers.

Most, if not all, LS swap headers you find on the market now have a slip-on cover that allows you to place the oxygen sensor at virtually any angle. This is a simple slip-and-slide add-on that is held on with a pressure clamp. I pointed mine straight in toward the transmission for maximum clearance to the road and floorpan.

The benefits of buying the engine mounts and headers together in a package is that these items are engineered to work as a unit and provide the necessary clearance. After all, you’re trying to package your engine and related parts in a particular F-Body car, so you need to be sure the headers clear the steering box and the frame. The two major areas of concern for clearance issues are the steering box and the frame. There’s no real process for figuring out how these fit together other than trial and error. I can say that if you buy all your components from the same place you are likely to run into fewer errors and interference.

When planning any build, you may run into a problem like this where the header touches something it’s not supposed to. In this case, you have a few options: You can dimple the headers, replace them, or swap in a newer and smaller steering box. If you have a manual steering box, you will not have any issues with clearance. However, I’ve seen a 50/50 ratio of cars that have clearance problems with the power steering unit. This just proves once again that using a system of complementary parts removes most of the guesswork. (Photo Courtesy Ryan Barichello)

Options are available for tight spots too, such as these block hugger headers. (Photo Courtesy Street & Performance)

These are the Hooker headers (PN 2288) that I used to mock up a set. You get everything in the kit you need: bolts, gaskets, headers, oxygen sensor, wiring, plugs, and collectors with bungs welded in for the sensor installation. Mocking up headers is a simple procedure in which all components are installed on the car and then clearances are checked. Steering components, hoses, etc. are kept away from the head and, of course, routing of the exhaust manifolds is crucial.

Most passenger-side headers are similar and do not have component clearance issues. Therefore, I only show you a driver-side comparison because often there are steering rod and other component clearance issues. Stainless Works specifically makes a version for the Speed Tech subframe (top). A universal version (bottom) is made by Hooker (PN 2288). Notice how the number-3 cylinder exhaust port is placed up and away from the steering components.

A variety of headers are on the market, from the stock iron manifolds from the factory to the typical longtube headers that are purpose-built for performance. Headers for this swap aren’t what anyone would call cheap. Prices typically start around $400. Some specialty headers can cost as much as $2,000. Choose wisely.

Stock

Let’s just get this out of the way: Stock F-body and Corvette LS1 headers do work on first- or secondgeneration F-Body cars. There, I said it.

A few nuances may be tricky but if you have an LS2, LS3, or LS7, you should be fine. If you have an LS1, you are golden in my estimation. For a budget build, these suffice until more funds become available.

These stock manifolds weren’t really known for making better power numbers, so it’s best to upgrade them now while you have the engine out of the car and have easier access. I have found that the better-fitting stock manifolds currently on the market are the 2010 and later F-Body headers; be aware that people have run into steering box interference on the driver’s side.

Aftermarket

Well before the current LS swap craze, enthusiasts were forced to custom fabricate or “Frankenstein” their own headers to fit into first- and second-generation F-Body cars. Fortunately, a number of companies now offer a variety of shorty, mid- and long-tube headers for various applications. These swaps have become so popular that there is little guesswork required for installing and fitting the exhaust. Proving yet again that if the trends are there, the aftermarket figures out a way the rest of us can join in and play. The following are the most popular header manufacturers.

Hooker: The Hooker headers that I test fit in my stock subframe worked quite well. A little tip here might be to install them from the bottom for the driver’s side; it just seems to work a lot better. The Hooker LS engine swap headers have laser-cut flanges, flat-finished TIG welded port sealing and are made of 18-gauge steel. The tuned-length primary tubes deliver a healthy horsepower bump, the 5/16- inch head flange offers excellent sealing for increased horsepower, and all the hardware is included with the headers. This particular kit fits both first- and second-generation F-Body cars.

Another header variation is the gasket mating surface thickness. The general rule is that the thicker they are, the less likely they are to warp and cause header leaks. Either of these versions has a sufficient amount of material thickness.

My Hooker headers came with step-down bungs for oxygen sensors. You’re killing two birds with one stone: a 3- to 2.5-inch reducer and a welded-in bung!

The Hooker header had plenty of clearance to the steering box, but it was quite tight. If you’re running a power steering box (not like mine), you might have to dimple the header or find another solution. Most folks just use a ballpeen hammer to make that indentation.

Sometimes fitting the headers can be difficult. I raised the engine an inch with a hoist. You can also use a jack supported by a board under the oil pan and then bring the headers up from the bottom.

Hooker’s black-painted headers are a good alternative for those who are budget conscious. They come with the obligatory 3- to 2.5-inch reducers with oxygen sensor bungs welded in for good measure. The headers come with gaskets, bolts, and oxygen wiring connectors if you need them. Overall, it’s a pretty good little package for the price.

Hedman: Hedman has built headers specifically for F-Body swaps in its Husler’s Muscle Rods Hedders and LS Conversion Kits so you can complete the install and avoid many fitment problems. Designed for 1970–1981 F-Bodies, these have a black ceramic coating and are available in a range of tube lengths and diameters. Longtube headers are also offered but for correct fitment and ground clearance you also have to buy the conversion kits.

The Stainless Works headers have excellent fit, finish, and performance for LS engines.

I decided on the milled finish of headers from Speed Tech and Stainless Works. Since they are made specifically for the subframe, I knew that they were the best bet for the build. You need to do your research and plan carefully for your particular project. That means asking around at many places and finding the best system for the application. When using parts designed as a system, you eliminate a lot of headaches down the road. Do most headers fit your application? Most likely; however, it’s a crapshoot if you don’t do your homework.

Stainless Works: Stainless Works likes to boast that they don’t do any sort of metal work that doesn’t involve some type of stainless steel, as their name suggests. I opted to go with a set of Stainless Works headers for this build for a number of reasons. The most important reason was that the headers were custom-built to work with my SpeedTech subframe and engine mount combination. I opted for a milled finish, but they also offer polished.

The Stainless Works headers worked just fine in the stock subframe clearing the steering box and other major components.

The headers fit the other side equally well.

Don’t forget the gaskets. They go in a particular direction, so pay attention to the orientation. These aren’t like some header gaskets that you could drop in from the top. These need to be installed with the header and gasket as one unit.

All of your stuff should play nicely with everything else. I had to modify the dipstick tube to fit the new thicker flanged headers. I used a cutoff wheel on a grinder to cut a notch in the bracket for the dipstick tube to match the header.

I was impressed with the headers and liked the weld quality. They came with 3- to 2.5-inch reducers and band clamps with welded oxygen sensor bungs for easy installation. They come loose so you can clock them in any position that fits best; I pointed mine inward to avoid hitting anything and keep wiring away from the hot pipes. I did have to supply my own gaskets and longer bolts to accommodate the massively thick flanges. I also had to snip off a bit of the dipstick.

You can see the amount of clearance I have on each side of the headers. It’s important to keep vital stuff out of the way, such as fuel lines, brake lines, and in this case, battery cables, because I plan to remote mount the battery.

This tech tip is from the full book, SWAP LS ENGINES INTO CAMAROS & FIREBIRDS: 1967-1981.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

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Oxygen Sensors

On newer style engines, the PCM uses oxygen sensors to balance the ratio of the air/fuel mixture. This, with a combination of engine temperature, ambient air temperature, and a few other parameters, allows the engine to run at its peak performance at any given moment. Oxygen sensors are crucial to your engine running smoothly. Do not remove them if you are running an EFI LS engine; not only does it throw a code constantly, but it doesn’t make anywhere near the power you want.

Mine are standard oxygen sensors; just make sure you use a little anti-seize. They are difficult to remove if they’ve been through many heat cycles.

I found this little factory wire clip. It seemed like a great place to hang the oxygen sensor wire and make sure the sensor doesn’t melt.

Installing oxygen sensors is pretty easy; just make sure you keep the wires away from header heat. If you don’t have sensors already in your headers you can mount them anywhere after the collector in any orientation. Just make sure that the welds are clean and have no leaks.

Make the connection at the wiring harness and you are pretty much good to go. The matching oxygen wiring connection is made specifically for the wiring harness so you are just about guaranteed to get these connections correct. Just make sure you connect the driver’s side and passenger’s side to the right connector.

Now, here’s where it can get kind of tricky. Since the late 1990s, the government has mandated that cars get a certain gas mileage among other things. One of those standards was to adopt the OBD II system that has two oxygen sensors per bank of cylinders, one before the catalytic converter, and one after. If you pull an engine from the boneyard that has four oxygen sensors and four plugs, don’t be alarmed; that’s perfectly normal. For all intents and purposes, all LS engines are OBD-II compatible.

Catalytic Converters

If you live in a place that doesn’t require emissions tests for older firstor second-generation F-Bodies, this section probably isn’t for you and you don’t have to run any type of catalytic converter or submit to any emissions standards. However, if you live in a state that requires those tests for your F-Body, there are a few options you can consider for your car to be emissions legal.

E-Rod

General Motors has come up with the E-Rod package (PN 19244805); the newest version is the E-Rod LS3. The engine is rated at 430 hp with 424 ft-lbs of torque. The package comes with an engine, ECM, wiring harness, exhaust manifolds, catalytic converters, oxygen sensors and bosses, fuel tank evaporation canister, fuel pedal, and air filter. Similar packages are available for the LS7 and LSA.

Other options are always available for completing an exhaust system, such as this 100-percent food-grade stainless-steel custom setup that was made to fit around the massive torque-arm rear suspension. (Photo Courtesy Speed Tech)

There’s no different strategy for exhaust after the headers on an LS swap for your F-Body. You only need to contend with the suspension in your imagination or go the normal route as shown here. (Photo Courtesy Stainless Works)

Everything else is up to the owner to provide or fabricate. You have to source a set of engine mounts, which can be easy to find and are relatively inexpensive. You also need to find a stout fuel system. General Motors recommends using the 4L60E automatic transmission (PN 19156260) with the matching GM controller (PN 12497316). If you want to go with a manual transmission, you have to order E-Rod package PN 19256487. At the time of this writing, both versions are priced at $9,375. Not bad considering it comes with a 12-month/50,000-mile warranty.

The package is CARB legal (California Air Resources Board), which makes it legal in all 50 states. You could think of this as a smog-legal version of the basic Corvette and Camaro SS engine. It doesn’t get any easier than this if you want something legal and almost plugand-play.

Stock Systems

Another option, albeit a timeconsuming one, is to grab all the smog parts required to make your car legal. That means you have to get the catalytic converters off the car or purchase new ones. In addition, make sure your ECM and wiring harness are set up for the extra two oxygen sensors. In addition, a part that everyone forgets about is the evaporation canister from the fuel tank. This is typically a black box that allows the recirculating gas vapors to return to the fuel tank. This is a critical piece that you have to source before becoming 100- percent smog legal. You can put in a set of aftermarket headers, but you have to figure out how to mount the dual catalytic converters. You need to route the exhaust pipes beneath the car and then bolt or weld the catalytic converters between the pipes and the mufflers.

A good thing about many LS variants is that they do not use EGR systems because they have camshaft overlap, much like LT engines. The C5 and C6 Corvette systems and F-Bodies don’t need the EGR for this reason and the same goes for 2003-and-later trucks.

After the Oxygen Sensor

If you aren’t forced to use a catalytic converter system, you’re pretty much free to come up with any system you want after the oxygen sensors. If you went with a long-tube header, you can pretty much bolt up your old setup, assuming you have the current reducers (if you need them). This isn’t a book on exhaust, so you’re on your own from the header back, but pretty much any aftermarket kit fits. It’s all a matter of brand loyalty and which sound you like.

There’s no different strategy for exhaust after the headers on an LS swap for your F-Body. You only need to contend with the suspension in your imagination or go the normal route as shown here. (Photo Courtesy Stainless Works)

In the case of my 1968 build, the rear-torque arm setup made life a bit more complicated and I was forced to be more creative. A well-meaning friend convinced me to install a Trans Am–style exhaust with each pipe dumping out on the driver’s and passenger’s sides before the rear tire. And this reinforces my point that after the oxygen sensors, you’re free to be as crazy as you want. Typically, many people install a dual muffler system with a crossover pipe in the middle and a rear-exit exhaust.

Induction

One of the last things you probably think of is the induction system. Regardless of whether you choose to use the mechanic throttle body or the drive-by-wire version, you need to figure out some way to deliver air to the new engine. You have to bring the intake tube out of the throttle body at a 90-degree angle and then to the air filter.

The best way to do this is to first figure out where you want the air filter to go. I wanted to route the air filter to the driver-side inner fender. Remember, the cooler air is farthest away from the engine; cooler air means more power and that’s a good thing.

Easier options are out there, such as this quick 90-degree bend to get it over with fast. (Photo Courtesy Texas Street & Performance)

On the LS9 intake, it’s easier to cut off the collar and remount it so that the intake tube can run more efficiently. (Photo Courtesy Mark Stielow)

After the new intake collar is on, the air flows straight into the intake, rather than making a sharp bend immediately. (Photo Courtesy Mark Stielow)

After mocking up the block-off plate and intake tube, you can get a better picture of what you’re making. (Photo Courtesy Mark Stielow)

For example, Nate Shaw fabricated my tube out of 4-inch aluminum tubing. He took several pre-bent forms (that can be purchased through a number of sources) and pieced them together by cutting and splicing. He worked with them until he had the correct bends. In this situation I couldn’t take it out the passenger’s side because the upper radiator hose gets in the way, so I had to route it out the driver’s side. Unfortunately, I had to snake the intake hose around the catch-can for the radiator since it protruded more than I thought.

With a tube this long, you have to find a place to mount it rigidly to the engine. I found the closest was the lower alternator bolt. Later, I TIG welded the pipe pieces together and matched the finish of the engine.

If you choose to make a tube or use something stock (such as a tube from Spectre), you have to remember to mount and hook up your IAT (idle air temperature sensor). If you’re running a MAF setup, it’s best to place it in a straight piece of pipe with some silicone elbows to make it fit properly.

Written by Eric McClellan and Posted with Permission of CarTechBooks

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The post Camaro and Firebird LS Swap: Exhaust and Induction Guide appeared first on LS Engine DIY.

This tech tip is from the full book, SWAP LS ENGINES INTO CAMAROS & FIREBIRDS: 1967-1981.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://lsenginediy.com/camaro-firebird-ls-swap-wiring-guide/

For a first-time engine swapper, buying and installing a complete wiring harness and adapter kit is the best option because creating or modifying a wiring harness and adapting the drive-by-wiring controls is incredibly complex. After all, you want to get the car on the road as soon as possible. Typical kits do not require an incredible amount of electrical acumen; in fact, many can be installed by connecting only four wires.

This is an extra feature on the AAW harness. It allows you to power virtually anything with 12-volt power. Some are key-on-only power and some are full-time power. It really beats having to splice into the main harness as in the old days.

The connector behind the starter tells you what engine you have. The gray one means you have a 58x system; a black connector indicates the older 24x system. Both work equally well to identify which is which for your ECU.

For this complete build, I stripped all the wiring and started over with an American Autowire 18-circuit kit. This kit is specifically made for the first-generation F-Body and it adds blade-style fuses, replacing the old barrel style. It also adds a lot of extra slots for accessories such as a banging stereo or even a power converter.

Although wiring may not be your favorite work, it’s often necessary to complete a project. One option is to pay a professional to do it, and certainly there is no shame in that. The LS engine is pretty straightforward when you can get it with a programmed ECU and matching wiring harness. Beyond that, there are a few common issues when performing this swap.

Gauges

The LS engine is a bit of an oddball when it comes to gauges and locations to put them. But the LS wire bundle is a masterful stroke of genius because you don’t have to wire anything you don’t want to! Since the ECU uses all of the vital parameters that you’d have on the dash to keep the engine running smoothly, you can tap into those systems quite easily using the wiring bundle from the LS harness. Most of these parameters, including RPM, water temperature, oil pressure, voltage, and more, are already coming out of the wiring harness. You need to wire it to the correct corresponding gauge in your gauge cluster. There can be a few exceptions and I cover the ones that you are most likely to need and run into.

The injectors and some of the other connectors have a different way of locking. You need to figure out the type of retention system and clip that needs to be pulled. In this case, the green clip needs to be pulled before the plug can be removed.

I got this Covan’s blank dash from Matt’s Classic Bowties. This allows a platform to custom install the Stack gauge cluster in the stock dash hole without having to custom make a dash panel. The Stack cluster comes with its own template. Make sure you really want this in the place you mark it; you only get one shot at it.

Every great journey starts with one small step and a small hole in the dash panel was mine. I went carefully around the perimeter with a variety of cuttings tools. First I drilled out the corner and then followed the scribe line with a jigsaw. I went slowly so I could precisely follow the scribe line. I also used a pair of shears to get the shape just right.

If everything goes well, this is what you should end up with. You need to install the four buttons near the cluster somewhere. Below the cluster seemed to be as good a place as any for it.

Two straps and a couple of bolts hold the gauge on the back.

Two adapters are an option for most projects. The PN 2277 (top) is the coolant adapter that plugs into the head converting the M12 x 1.5 fitting to allow you to use a 1/8-inch NPT coolant sensor. The oil pressure adapter (P2268, bottom) comes in at M16 x 1.5 and also adapts to the 1/8-inch NPT fitting. (Photo Courtesy Auto Meter)

The American Autowire kit comes with everything you need. It even comes with a new ignition lock cylinder and head light switch. They give you plenty of extra wire so if you take your time, it works out really well.

I know this looks intimidating, but if you go slowly and follow the instructions and wiring diagrams, everything will work.

You need an array of tools and hardware to help you in the wiring process. Some shrink tape, wire cutters, and a wire stripper are required to make the necessary electrical connections and complete your wiring job.

Because I am taking the positive terminal from the trunk I had to bend the terminal to match the bend to the starter.

You need to use heat shrink to end up with a properly wired terminal like this.

My new 18-circuit fuse block bolts right into place without any modifications, so I didn’t have to drill the firewall. The AAW kit is meant to bolt into the stock location, which is a delight. It offers the use of blade-style fuses with larger amperage capabilities and more circuits to work with instead of having to overload the old stock system.

I went through the diagram and located several unused wires, so pulled them from the firewall connector. You need to compress the tabs on the connectors and pull them out of the plug.

This diagram illustrates the correct wiring for a resistor to go inline for your tachometer. The resister needs a 12-volt key-on source to allow it to work properly.

I am pointing at the water plug that can be used for virtually anything to do with the coolant. This hole measures M12 x 1.5. If you’re looking for an adapter, it needs to be this size. Most gauges do not fit this size and need an adapter. Mechanical gauges are usually too big for the adapters, so you have to run an electric gauge or figure something else out. If you’re going this far to put an LS engine in your car, don’t scrimp on the gauges, they are cheap insurance. (Photo Courtesy Auto Meter)

The smaller of the two sending units is the electrical sweep unit. They are solid state, and therefore Auto Meter claims they are less prone to failure from vibrations like its mechanical cousins. The larger unit can be difficult to fit because it takes up more space. In such cases Auto Meter recommends using a piece of braided hose to relocate the unit to a lateral position. This does not have an impact on the reading of the gauge. (Photo Courtesy Auto Meter)

A smaller and shorter water temperature sending unit (PN 2259) is shown. This allows you to save space when mounting on the head. (Photo Courtesy Auto Meter)

Tach Wiring

Tach wiring is fairly straightforward; it is spliced in from the wiring harness and ECU, typically PIN 10 and a white wire (1999 to 2002 have a red connector, 2003 and later have a green connector). In most cases, all that is required beyond the wire hookups is that the tach itself should be set to 4-cylinder or 6-cylinder mode depending on the make and model of your gauge. Sometimes you need to tap the coil wires themselves (usually pink) to run to your tach.

This takes care of most LS tach wiring; however, a few people require a small additional resistor known as a “pull-up” resistor. A wide variance is possible for those who may need to modify the tach signal. You know pretty quickly if you need to do this when you start up the engine and the tach acts erratically or reads inaccurately. Today’s aftermarket tachs require a ground wire as well as a 12-volt source and exciter wire. The exciter wire is the one that can necessitate the “pull-up” resistor.

You need a 5,000-ohm 1/4-watt resistor or a 4,800-ohm 1/4-watt resistor. Often a 680-ohm 1/4-watt resistor works; a best practice is to start with the 5,000-ohm 1/4 version and work your way down. Besides, resistors are cheap and plentiful. You need to run this wire from a fuse-protected keyed (only operates when the key is turned to “on”) 12-volt source and then spliced into the wire from the harness to the tach. Start it up and see if it’s working.

Water Temperature

The LS engine has a variety of ways to measure water temperature. Most notably are the two ports on each cylinder head. On both heads they are at the same location, farthest to the driver’s side of the head. You’ll find a plug that needs an M12 x 1.5 adapter to run an electric gauge. Because the size of the hole, a mechanical gauge doesn’t fit.

Auto Meter has made an adapter for the electric sending unit (PN 2277). This adapter fits right in and has a 1/8-inch NPT port that accepts most sending units. Auto Meter warned me that a smaller sending unit (PN 225) might be needed.

This tech tip is from the full book, SWAP LS ENGINES INTO CAMAROS & FIREBIRDS: 1967-1981.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://lsenginediy.com/camaro-firebird-ls-swap-wiring-guide/

The adapter (PN 2277) is installed in the head. I recommend using a thread sealer to prevent leaks and as the aluminum and brass are soft metals. Be careful not to deform the fitting when tightening it. (Photo Courtesy Auto Meter)

The head is already pre-drilled and tapped to accept an electronic sending unit, which is installed in the head. (Photo Courtesy Auto Meter)

I had to use an inline water temperature gauge for the stack unit as the sending units are too large to fit any of the regular places without drilling and tapping a very expensive cylinder head.

The oil filter port is used to adapt the pressure gauge. It is located just above the oil filter on a stock LS engine. (Photo Courtesy Auto Meter)

Just as on the small-block Chevy, the oil pressure port is located at the back of the engine. (Photo Courtesy Auto Meter)

The adapter (PN 2268) was installed on the engine. Be sure to thread the fitting as far in as you can to flatten the washer. Do not over-tighten as these fittings can snap off. (Photo Courtesy Auto Meter)

For my Stack cluster, I wasn’t able to use the larger fitting because the bore was too tight for the sending unit. I thought I could be clever and bore out the fitting, but that ended in failure. I turned to the heater hoses instead. I used an Auto Meter (PN 2280) to help. It’s a 5/8-inch hose adapter that accepts the 1/8-inch port size. I used 5/8 inch because it is the “feed” side of the heater box, meaning that hot engine coolant enters the heater core through this hose and exits out the 3/4-inch hose.

Oil Pressure

The LS engine has an oil pressure plug similar to the small-block in the respect that they are in the same vicinity. That’s about where the similarities stop. This plug requires a special adapter to run 1/8-inch NPT sending units. Auto Meter sells a brass fitting (PN 2268) that allows you to use this pressure port for the cockpit gauge. Auto Meter reports that you can run a short piece of pipe or braided hose from the oil pressure side and it does not diminish any readings you get from the gauge!

Here’s where a few things get tricky. The engine harness needs a port to tell the ECU how much oil pressure is being generated. That typically is the back slot behind the intake in the traditional location. If you use this for your gauge, you have to figure out something else to make the ECU happy,

The solution is a modification to the oil cover plate located right above the oil filter. The oil pan from Mast doesn’t have this option, but I show you how to solve that problem. Drilling and tapping this plate gives you an excellent way to add a gauge without making any unsightly changes. You need to keep everything away from the heat since the headers are directly in front of this piece.

Oil-Pressure Sending Unit Installation

Step 1:

You need to cut off the excess material to make room for the NPT tap, which is tapered. Don’t cut off so much that you have nothing left to thread to. However, you need to remove roughly 1/2 inch to fit the sending unit. (Photo Courtesy Auto Meter)

Step 2:

Use a 5/ 16-inch drill bit to enlarge the center. (Photo Courtesy Auto Meter)

Step 3:

Chase the drilled out section with a 1/8-inch NPT tap. You need to go slow and steady to properly clean metal shards out of the oil filter port. You obviously don’t want metal debris fl owing through your engine. (Photo Courtesy Auto Meter)

Step 4:

You can now screw the oil pressure sending unit into place; snuggly so as not to leak but not too tight to cause a crack.

For my oil pan, I had to be a bit creative. I quickly noticed that the oil pan doesn’t have the typical plate that can be modified. It only has two -10AN ports that are meant for an oil cooler (I mentioned that Mast doesn’t mess around when they build engines, right?). I called Mast and they informed me that the rearward-most port is the “feed” line and provides accurate oil pressure readings. Just as with the stock oil plate, I was able to drill and tap the aluminum -10AN fitting to accept the 1/8-inch NPT sending unit. I added a 90-degree elbow to clear the side of the block to allow the sending unit to clear and not interfere with the hot header. I plan to take the advice from Mast and add an oil cooler.

Oil Temperature

The good news about the oil temperature gauge is that it doesn’t need any pressure; it only needs to be submerged in hot oil to work properly. There are several ways to get the proper oil temperature. You can branch off the oil-pressure sending unit with a T-fitting or you can make its own special slot. Chances are, your wiring harness isn’t using the low-oil-level sending unit. On the passenger’s side of every LS pan is a plug that the stock harness uses for an oil level warning light.

I was able to find the right fitting for my 1/8-inch NPT sending unit. I used a specialty pre-tapped aluminum fitting from Speedway Motors (PN 481201). It allows me to use the sending unit and not make any major modifications. Typical operating temperatures for the LS engine are roughly 195 to 210 degrees F. If you plan to track your car and start seeing temperatures above 275 consistently, you need to add an oil cooler.

I tapped into the right side of the Mast oil pan to access the pressure side to get an oil pressure reading.

After drilling and tapping the appropriate 1/8-inch NPT hole, I reattached the oil pressure–sending unit.

This is a Speedway Engines adapter (PN L-0201). The oil pan temperature replacement plug allows you to have a port for the oil temperature with a 1/8-inch NPT tapped port.

You might have to remove the sensor to get the fitting in. Remember to use a little Teflon tape to seal any air leaks. Thread it into the head by hand until it is snug.

The brown port behind the starter is the oil level sensor. Removing it with a socket or wrench allows the adapter to monitor the oil temperature.

Fuel Pressure

You must maintain the correct fuel pressure of 58 psi at all times in an LS engine to realize maximum performance. I used an -8AN adapter from Earl’s that allows me to run a 1/8-inch NPT solid-state sending unit that matches the stack EFI injection stack unit (PN AT100196ERL).  

To check the fuel pressure, insert the key into the ignition and turn it to “on” so the EFI system primes itself. It should turn the fuel pump on for 2 to 5 seconds and shut off if the car is not running. This allows you to check the gauge and fuel system leaks.

Wiring Harnesses

A number of automotive businesses, including Painless Wiring and American Autowire are more than happy to build a wiring harness for you. It will be more costly, but it’s an option if you don’t have a lot of time. You can, of course, build your own wiring harness as I have shown you.

Both companies make great kits to suit any need and in many cases make kits that far supersede anything that came from the factory on the first- or second-generation F-Bodies. I chose the American Autowire kit because I’ve had experience working with their systems and felt comfortable using them again. The best advice I can give you is to go slowly! Take your time and work with the components one at a time. It can be a bit daunting when you see all the wires in one giant bundle, but if you look at each circuit individually the bigger picture tends to take shape.  

You need to know a few things up front before you order a harness: the transmission needs, whether you are sending a harness to be reworked or purchasing one, the length of extra harness (crucial if you want extra to mount the PCM under the dash), the oxygen sensor requirements, and the fuse/relay box needs.

You can use a wiring harness from a junkyard or you can have one made out of whole cloth but you should be prepared for some extra cost.

Fabricators usually ask questions about your particular build. You need to determine which computer you are going to use and specify which transmission will be installed. If it’s an automatic, you need to program the ECM’s shift points and transmission functions or you’ll have to use an external stock ECM or aftermarket version. You also need to determine if you are going to be running A/C. In addition, you need to decide whether to use a speed-density system or a mass air system.

The final consideration is the length of your harness. To figure that out, you need to decide on the mounting location of the computer because that dictates the length of the harness. You can mount the ECM in the passenger’s compartment and run the wires through the firewall. If you choose this placement, you need a longer harness than if you mount the ECM in the engine compartment.

Wiring Harness Installation

Step 1:

The Mast wiring harness comes pre-labeled with many of the popular connectors already marked. It’s nice when things are so easy. Since the Mast harness is customized and pre-routed for the particular engine, connecting the wires is a no-brainer. Decisions about the fuse box and ECM are crucial. Those need to be free from heat, free from vibrations, and in an easy-to-access area.

Step 2:

Here’s the Mast wiring harness that came with the engine. Everything is well laid out and fits to the block (doing its best to remain hidden).

Step 3:

The M-90 DBW ECU from Mast is a pretty solid piece. It comes with rubber grommets. It’s up to you to find a good place for it away from vibrations, heat, and excess moisture.

Step 4:

This is the original gas pedal; it has to go. The drive-by-wire pedal will be mounted to the firewall.

Step 5:

This jumble of wires is not as confusing as it looks. Everything has a place and there is a place for everything. Go slowly and it will make sense very quickly. Because each wire has only one way to be routed and only one specific counterpart to be plugged into, routing/connecting the wires is a simple procedure. After it’s clicked into place, tuck the wire behind anything close, such as the injector.

Step 6:

The American Autowire (AAW) kit replaces the old front body harness further along in the build.

Step 7:

Removing the old wiring harness can be difficult but if done carefully I can probably resell it at the swap meet and maybe recoup some of the cost. Many of the wires from the factory are held in with bent tabs or clamps. It pays to follow each wire cluster until you get to a junction then gently remove it.

Step 8:

Here are the original gas pedal (left) and the new DBW gas pedal (right) side by side.

Step 9:

Once all the wiring has been removed, you can start to plan your wiring setup more carefully.

Step 10:

Here’s everything you get in the AAW wiring kit: a new ignition switch, bright beam switch, and headlight switch.

Step 11:

The idle air temperature sensor is an easily missed connection. This one just plugs 10 directly into the K&N air filter.

Step 12:

The Mast harness comes with three connectors under the dash in addition to the main wire bundle. They are: OBD-II port (upper right), drive-by-wire port (right), and ECU interface (left). Determine the location in the foot well to mount it, drill two pilot holes, and then screw the plug down with sheet-metal screws. Your wiring harness most likely only has the OBD-II port and drive-by-wire plug.

Step 13:

To get all these wires in the dash, I had to cut a 3-inch access hole in the firewall. I use a 3-inch rubber grommet to make sure air and gases don’t enter the cab. Placement of the hole depends largely on what you want to do. If you want a hole closest to the gauges for ease of wiring such as I did, this is a good location. Others have put a hole behind the engine to hide the harness. The choice is up to you.

Step 14:

This is the bundle that comes out of the Mast wiring harness. Most of these wires aren’t necessary for the entire wiring. Some go to gauges while others are crucial, such as ignition and key-on cycling. Wires that are not used are capped. It helps to have the wiring diagram handy to make sense of it all because each wiring harness is slightly different. This harness came with a set of instructions. I pulled back a good part of the sheathing to reveal the wire markings to determine which was which.

Step 15:

A ground strap can be found at any local auto parts stores, and you need to be sure your electrical system is properly grounded. Because this frame was powder coated I had to scrape some off to make sure the ground strap had excellent metal-to-metal contact.

This tech tip is from the full book, SWAP LS ENGINES INTO CAMAROS & FIREBIRDS: 1967-1981.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

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Wiring Harness Hookup

Don’t let this giant bundle of wires intimidate you. I like to call this type of automotive work a “process of elimination.” Once the engine arrived at my place, I promptly removed the wiring harness and started working on the engine accessories and other pieces. After a while, the harness had to go back on and I couldn’t remember the right way to install it. Thankfully, the weather pack plugs and configuration allowed me to figure it out quickly. It’s pretty hard to mess this up when everything has a specific place and corresponding connector. If you organize them, everything should go smoothly.

Chances are that your wiring harness is original and looks a lot like mine. While it’s entirely possible to put an LS engine in your car and get it working well, installing an updated kit, such as the AAW kit, can make life a lot easier.

To remove the original gas pedal, remove the two bolts holding the pivot arm in place. A simple socket does the job even though it can be a bit of a pain and the plastic holder can easily break. Remove the cable from the pedal and it should fall right out after removing the bolts located on the firewall that hold the pedal lever in place.

Length of Harness

Any wiring harness company worth anything asks you how much “extra” length you want in your harness. The extra length allows you to mount the ECM and the fuse block in a suitable location. The location determines how much extra length you need. I’ve seen extra lengths range from ultra-short (where the components are mounted in the engine bay), to super-long, as in 3 feet or longer (to accommodate mounting inside the passenger compartment). This extra bit determines where you can put your ECM in the vehicle. It might be worth figuring out where you want to put your computer well before you order a harness.

OBD-II Port Location

Any wiring harness should come with an OBD-II port. This is a standard port for all newer vehicles. It allows you to plug in a scan tool or laptop to “talk” with the PCM to program it further or troubleshoot codes that are being thrown.

The wiring harness side is a female 16-pin J1962-type connector with two rows of 8 pins. The government standards mandate that this must be within 2 feet of the driver’s position. This is the best position because it allows you to use the scan tool or laptop while in the driver’s seat to turn the car on or off with the key.

I located it under the dash within easy reach and away from the pedals. Of course you can position it anywhere you like. People who want the clean look put it in the glove box.

Written by Eric McClellan and Posted with Permission of CarTech Books

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The post Camaro and Firebird LS Swap: Wiring Guide appeared first on LS Engine DIY.

General Motors designed the LS platform with much platform commonality. Similar to the common engine mount bosses on all LS engines, every LS engine uses the same transmission bolt pattern. The bolt pattern layout allows for a direct bolt up of all LS-compatible transmissions, so 4L60E, 4L80E automatics bolt up and so does the Tremec T56 and other similar manual transmissions. However, you don’t need to use a current transmission. You can use a classic transmission, such as the Muncie M20, M21, and M22, or Turbo-Hydramatic 350 and 400. These were industry-leading transmissions for their time and while you may be able to find a more efficient modern transmission with an overdrive gear or ones with the particular ratios you are looking for, these still remain capable transmissions. Mating a classic transmission originally made for the Gen I Chevy small-block is not difficult. The classic Chevy transmission bolt pattern has one less bolt than the modern LS transmissions. So when installing the transmission on the LS, you leave out the passengerside center bolt, which would enter the water jacket of the LS block.

You need to find the pinion angle of your drivetrain to match it to the rear end. A $10 angle finder like mine makes it fairly simple. A general rule is that 3 degrees is sufficient for street use.

This tech tip is from the full book, SWAP LS ENGINES INTO CAMAROS & FIREBIRDS: 1967-1981.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

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Many new transmissions are available to harness the power of the LS-series engines and direct this power to the rear axle. A myriad of automatic and transmission options are available for LS engines and F-Body swaps. After all, transmissions play just as much of a vital role in a build as the engine does. Also, in defense of the mostly unseen transmission, it is probably one of the major factors in how much fun a car is to drive. It’s amazing how easily a manual transmission suddenly turns a pretty average driving car into a race car.

You will most likely have to modify your driveshaft to fit your new engine and transmission combo. I don’t have the capability to do this myself so I measured for a new driveshaft to be built. It may not look like much here, but a couple of inches does make a difference in proper fit. The new shaft (top) is made by Bear’s Performance. The original shaft (bottom) was shortened for my small-block Chevy and Tremec T56 Transmission. A machinist needs to do any shortening.

Because of the new power demands, I asked Bear’s Performance to beef up the components. I upgraded the driveshaft as well as new 1350-style U-joints. I went from 450 hp to 600 hp. I also swapped the old 10-bolt for a Ford 9-inch rear end.

You will most likely have to cut a new access hole for the transmission shifter. So you measure it, mark it, and use a cut-off wheel to shorten it to the correct length. I tried to use the old hole, but as you can see, it’s a bit off. Installing a fireproof shifter boot is a top priority. It’s typically easier to remove the carpet before modifying the floor panel. I used a cutoff wheel on a grinder and a tin snip to make the final cuts.

In this article, I cover the basics and some subtle nuances for putting just about any transmission in the GM lineup behind an LS engine into a first- or second-generation F-Body. In all the transmissions I’ve seen swapped behind LS engines in these cars, I have yet to see a stock location engine/transmission combo that needed the transmission tunnel cut. There are those who have had to cut and modify the transmission tunnel, but typically these are for very specific reasons, such as having the engine raised higher than the stock location, lowered, or broken body mounts.

In the following case, Mary Pozzi’s car needed a new tunnel because she wanted to shove the engine farther back for better weight distribution. In such a situation, you certainly have to cut the floor and tunnel; otherwise feel confident that the stock tunnel can remain intact.

Thankfully I started out with a fairly solid Camaro body. The transmission tunnel doesn’t need to be cut up. Contrary to popular belief, you don’t have to cut the transmission tunnel to get a T56 to fit well. If you have a modified frame mount or lower than usual mounts, this may change.

The back of the LS engine is different in two major ways. First, it doesn’t have the familiar 1 o’clock position bolt, and second, it’s .400 inch from the back of the engine to the flange that mates the transmission to the engine.

The obvious difference between the blocks is shown here. The upper right bellhousing bolt has been eliminated but it does not affect performance of the bellhousing or its strength.

T56 Install

I suspect that this transmission is the most likely candidate for hot rodders building an F-Body, and for good reason! Most variants of the T56 can withstand at least 450 hp and 450 ft-lbs of torque, which can usually fit most builds. The T56 is also a killer road-race transmission. With a choice of close and wide ranges of the first four gears, you have a great selection of how aggressive you want to be.

In addition, the T56 is an excellent cruising transmission that has two overdrive gears. Not one, but two! With fourth gear being a 1:1 ratio, the two extra gears are just a bonus. Chances are that you probably won’t ever need sixth gear as most people running this setup have to be running 75 to 85 mph to ever see the benefit of it, but it’s nice to know that you can run 75 mph down the highway at close to idle speeds.

The only downside that I see with the transmission, and my only gripe, is that this bugger is big and heavy. The T56 weighs around 125 pounds where a typical T5 runs a mere 85 to 90 pounds. Still, the extra weight is worth it.

Tremec T56 Transmission Installation

Step 1:

I like Tranzilla transmission fluid because major race teams use it. If it’s good enough for them, it’s good enough for me. It’s a fully synthetic oil that protects greater than stock OEM fluid.

Step 2:

The ATS T56 crossmember fits as well in a stock frame as it does in a modified one. It has lots of adjustability and cutouts to fit the exhaust snugly to the floorboard. Use Grade-8 hardware to bolt it into the same location as the stock crossmember.

Step 3:

The clutch slave cylinder has been installed; two bolts on either side that go into the transmission. The top port is used for bleeding the system while the lower port is used as the quick connect for the master cylinder.

Step 4:

This crossmember came with the Speed Tech frame. It’s fully adjustable forward and backward to accept virtually any transmission I can throw at it. Grade-8 hardware fastens it to the frame.

Step 5:

The correct bolts were not included with the slave cylinder so I had to source them from the local hardware store. They are M6 x 1 x 16 mm. Torque them to 25 inch-pounds.

Step 6:

Use a dab of red or blue Loctite. Slowly guide the transmission into place, being careful to seat the input shaft snugly into the pilot bearing. You should have a buddy help in the process because the transmission is heavy and difficult to move into position. You could use a floor jack to slide the transmission into the proper position in the transmission tunnel.

Step 7:

Whether it’s behind a small-block Chevy or an LS engine, the ATS crossmember works well. The ATS piece reuses a stock TH400 transmission mount to secure it to the transmission and crossmember. It mounts and bolts in just as the stock transmission does. Tolerances on these pieces are tight so be prepared to do a fair amount of maneuvering.

Step 8:

The Speed Tech frame uses the same transmission mount as the ATS piece. It’s secured with two bolts. I left the bracket bolts loose to make up for any slack the transmission needed to take up.

Step 9:

This is a good close-up of the transmission crossmember that comes with the Speed Tech front subframe. It has a lot of front-to-back movement that allows me to place the engine and transmission virtually anywhere I choose. Using Grade-8 bolts, the crossmember just sits in place on top of the frame and is bolted in.

Step 10:

The T56 is fully mounted. The two openings in the front transmission plate are for the hydraulic clutch. The top one is the bleeder screw and the bottom one is the quick-disconnect port.

Step 11:

I pulled out the ATS T56 crossmember for a good look at this three-piece unit.

Step 12:

The clutch master cylinder from General Motors (PN 12570277) has an input shaft that needs to be shortened. I purchased a Speed Tech conversion kit and went to work cutting off the old sleeve. I used a cut-off wheel and pliers to remove the old arm. Be careful not to go too deep when cutting it off the sleeve or you could ruin a very pricey item.

Step 13:

After removing the old sleeved shaft, you are ready to install the new joint. You use a vise to compress these two together and a chisel to dimple the shaft. The threaded piece is for the pivot arm. The tube must be pressed on; it’s not threaded on the inside.

Step 14:

After your master cylinder is mounted, you have to find a safe passage to the transmission so that the braided line isn’t kinked and is far away from any heat from the headers.

Step 15:

Mount the master cylinder reservoir close to the pedal and make sure it’s at the highest point possible to prevent any air from entering the system. This helps in gravity-bleeding the system. I used sheet-metal screws to secure it to the firewall.

Step 16:

Here’s how it should look when you are finished. Two bolts hold the master cylinder onto the booster and four bolts hold the booster to the brackets. Using sheet-metal screws the reservoir should be mounted high so that it is the highest point of the system and out of the way.

Step 17:

I had to make a significant modification at the arm coming out of the firewall to the clutch pedal. I removed the clutch pedal and drilled and tapped a hole for the clutch. The original holes are not in the correct location nor are they the correct size. You have to take the pedal out of the car.

Step 18:

The engine and transmission are mated up and ready for the initial install. You usually have to install the engine and transmission assembly several times to ensure the steering linkage doesn’t interfere with engine parts. Moving the engine back also presents issues; the headers may not clear the upper control arms and cross-shaft bolts. (Photo Courtesy Mary Pozzi)

Step 19:

Because Mary wanted to move the engine and transmission farther back than the stock location, the transmission tunnel most likely required modification to allow proper fit for the transmission. (Photo Courtesy Mary Pozzi)

Step 20:

Here’s the position of the tunnel after the initial trial fit. Additional metal is cut and welded to strengthen and reposition the original sheet metal so the transmission fits. (Photo Courtesy Mary Pozzi)

Step 21:

The transmission tunnel was enlarged. It was spot-welded and fabricated with a little more room for the transmission. (Photo Courtesy Mary Pozzi)

The differences between the LT T56 and the LS T56 hydraulics are shown. The LT version (left) has a plunger that actuates a fork that pivots inside the bellhousing while the LS version (right) uses hydraulic fluid (DOT 3 brake fluid) to actuate a slave cylinder attached to the transmission.

This is a good comparison of two master cylinders: a fully hydraulic LS version (top) and a hydraulic master and mechanical fork version for LT-style transmissions (bottom).

Bleeding the Clutch

One of the jobs that people seem to complain the most about is bleeding the clutch. There’s no secret here that General Motors didn’t necessarily make this the easiest job in the world, but it also isn’t impossible.

Note that all T56s use a 7/16- inch wrench to open the bleeder. Do not let the reservoir become dry and always keep it topped off with DOT 3 fluid.

Here are three easy ways to bleed the clutch slave cylinder:

Gravity Bleed: This method is straightforward. Just open the reservoir cap, crack the bleeder with your wrench, and crack open a beer. It helps with the mess if you choose to use a catch can and to put a clear hose on the end of the bleeder to view the fluid. Wait for the fluid to start leaking out and you are good to go. This method is the slowest and often time doesn’t always work. You can jump start the gravity bleed by lightly pushing the clutch pedal, but don’t go crazy with it.

Hand Pump Bleed: This method is for the one-person show. The best way to complete this task is to use a hand pump just like the one you use for bleeding brakes. Open the reservoir and twist-open the bleeder. Use the vacuum pump just like you would a typical brake system. Make sure to keep an eye on the reservoir, letting that go dry makes your job much, much worse.

Traditional Bleed: The traditional way to bleed the clutch is just like a two-person brake bleeding operation. One person is in charge of the pedal and the other is in charge of the bleeder. The idea is exactly the same as a brake bleed, one person pushes the pedal down and barks out, “ON!” and the other person opens the bleeder to allow fluid to travel through the system. After the pressure is moved along, the bleeder operator informs the pedal person, and the process is repeated until all the air is out of the system.

T56 Connections

The T56 has a number of connections on each side of the transmission. The three that you’ll be using are the vehicle speed sensor (VSS), backup lights, and reverse lockout solenoid. Depending on which speedometer you have, the VSS does or does not directly plug into the transmission. Most electronic speedometers are compatible with the transmission but need to be calibrated to it. Some may require an additional converter if your speedo is mechanical. ShiftWorks has a comprehensive kit that allows you to run a mechanical speedometer, but this requires replacing the tailshaft and slightly modifying the existing shaft. This is a really good option if you want a clean install.

This tech tip is from the full book, SWAP LS ENGINES INTO CAMAROS & FIREBIRDS: 1967-1981.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://www.lsenginediy.com/firebird-camaro-ls-swap-transmission-guide/

The other option that is fairly popular is the Cable-X system. It’s a small electric box that converts the pulse signal from the VSS into a mechanical feed. They claim that this box works with virtually any speedometer on the market, and for the amount of work it takes, it’s a good price at around $300.

Reverse Lockout Solenoid

A quick word about the reverse lockout solenoid: You can wire this up, but I frankly feel it is almost not worth the effort. With the reverse lockout solenoid hooked up, you have to shift hard into fifth gear and slam the shifter into reverse. It’s virtually impossible. The T56 shifts into reverse in conditions under 5 mph or basically stand-still. All that you need to do is just give it a little tap and the transmission shifts into reverse. For this very reason, most people I’ve seen just leave this alone and don’t plug it in. It’s your call.

Speedometer Output

Adding a speedometer to a T56 is fairly easy to do if you have the correct speedo. Options are available for those who want to use the stock speedo or one that is mechanically driven, which just takes a bit more work.

Right off the bat, almost any electric speedo works with the T56 output in the tail shaft. One wire is the exciter wire and the other is the ground. More times than not, getting the wires right doesn’t really matter as long as you have both hooked up. However, you have to make sure that you calibrate the speedo. This usually involves driving a certain distance and hitting a couple of buttons. This is a requirement of most mainstream gauges, such as Auto Meter speedos.

My Stack unit is a bit on the odd side and requires a pulse amplifier and a little math. I had to push the car forward one full revolution of the tires and measure the number of pulses. Then using the length of one tire rotation I was able to calculate the number of pulses per mile and enter that into the Stack unit; a bit more lengthy, but equally effective.

Now, for you interior purists who just can’t live without your factory speedometer, you are in luck. You have two options. The first is to replace the tail shaft with one that allows for a mechanical input such as the ones from ShiftWorks. The other option is to run a Cable-X system. This converts the pulses from the transmission into mechanical movement. It’s a simple three-wire setup that can be hidden under the dash.

Throwout Bearing Spacing

I had difficulty setting the correct throwout bearing clearance when mating the T56 to my LS3 combo. The clutch and the bearing must have 0.200 inch of clearance between them. If the clearance is too great, the throwout bearing extends too far and causes premature wear. On the other hand, if the clearance is less than this spec, the clutch disengages. This causes slippage in the clutch and effectively makes it seem as if you’re riding the clutch, even when your foot is off the pedal.

Aftermarket spacers can be used to attain the correct clearance. Most speed catalogs, such as Jegs and Summit Racing, sell spacers and shims in various packs starting around $20. This is typically a bigger deal when purchasing an aftermarket bearing or a rebuilt one, as the tolerances are most likely not the same as factory stock.

Tremec Magnum

The Tremec T56 Magnum variant of the standard T56 is able to handle upward of 700 ft-lbs of torque while the stock T56 is typically rated at 450 hp and 450 ft-lbs of torque. The Magnum has a very short shifter throw with a very sharp engagement in the syncros when the shifter is maneuvered. The Magnum is roughly the same size as the T56 and looks very similar; it is a bit longer, almost 2 inches in overall length, so you have to shorten your driveshaft. The Magnum has two different gear sets: 2.66 or 2.97 first gear. I decided that the 2.97 first gear was more optimal for this application and for auto-crossing where the courses seem to be tighter and it allows me to dig out of the hole just that much more quickly. The two overdrives are another bonus (just as the stock T56 provides), so in my world it’s the best of both.

The Magnum is a versatile transmission and it has three important design features to note. First is the reversible shifter. It allows for more varied placement of the shifter, which may allow you to reuse the stock shifter location with minimal cutting and prodding. Due to loose tolerances in the manufacturing of F-Bodies in the 1960s and 1970s, you may have to dimple the floorpan with a ballpeen hammer in a couple of places to make sure it fits properly. With my T56 I didn’t have to do this, which is the norm; others may not be so lucky.

Second, the Magnum can use either a mechanical or electric speedo attachment, and this is great news for anyone who wants to run stock-style mechanical gauges.

Third, the Magnum has provisions for a Ford-style mount or the traditional TH400 GM mount.

If it’s good enough for the ZR1 Corvette and the Dodge ACR Viper, it is suitable for the LS3 in my car. The shifting actuation, or shifting feel, is quite different than the typical clutch-bang-gas type of driving; rather, the Magnum is shifted with a light touch for optimal performance. The transmission I chose is the Tranzilla from Rockland Standard Gear (RSG). RSG first takes a Tremec Magnum T56 transmission, then adds a Viper tail shaft, and reworks some of the rings to make them handle roughly 1,000 ft-lbs of torque and abuse. With this transmission, you cannot reverse the shifter and it does not have a mechanical speedometer output. Instead, it only has an electrical speedometer output. But it has so many advantages. Regardless, I know that the RSG Tranzilla is able to keep up with me even if I upgrade engines or decide to add a power adder such as a supercharger.

New-Style Transmissions

One option for your transmission is to buy an engine and tranny combo all in one. You should also buy the main ECU and transmission controller as a single unit. If you have a manual transmission you can skip this section because you don’t need it. If you don’t, I cover the basics of installing a modern transmission with the LS beast.

4L60E/4L80E

The newer and more modern upgrades of timeless classics such as the 700 R4 and TH400 are great ways to get out on the road quickly and reliably. These bolt directly to your LS engine with no worries about modifications. The only catch is that these transmissions require a computer-assisted controller to make sure everything works properly. The 4L80E is a bit more robust and can be built for high-horsepower applications. The 4L80E case is larger than the 4L60E but neither should require transmission tunnel modifications. The only decision left is really what shifter you want to use!

The 4L80E is a great automatic transmission. It can be built to almost any power level and still provides a smooth ride.

GM Controller

If you choose to go with a modern automatic transmission, you have to find some way to control it. If you have created your own harness, you probably already have the proper connector and a built-in transmission controller. You can also specify to the maker of wiring harness that they include the proper wiring for your specific transmission; it just helps keep things clean and less complicated.

Of course there are aftermarket options for almost everyone. The obvious one is the standalone computer and harness from General Motors (PN 12497316). They come as a kit and can be used to control the 4L60E, 4L65E, 4L80E, and 4L85E line of transmissions. The kit comes with the computer connector and the ability to program virtually any parameter. A lot of other controllers may be on the market that do a swell job just like the GM controller, but for the vast majority of people, this controller does the trick quite well.

OptiShift Controller

For those of you who need a more programmable option, OptiShift has a slick controller unit that costs around $600 depending on application. This option can be fully programmed with a laptop and even has a cool-looking readout for temperature, sensor values, and fault codes. I’ve seen them in action and I am fairly impressed with how this unit functions. This might be a good option if you have a high-horsepower application and want a bit more control over your transmission functionality.

Classic Transmissions

When it comes to the installation of older-style transmissions into first- and second-generation F-Body vehicles, there’s good news and bad news. The bad news is that things become a little more complex than the standard bolt-it-up way I am used to doing things.

First, you have to make sure that your wiring harness is correct. Whether you order one or make your own, you want to be sure the harness matches your transmission style. Most companies make sure it’s the correct harness, but it never hurts to triple-check. For example, in the case of the T56 or other manual transmissions, you don’t need an external controller like the newer-style automatics require. This makes life a lot simpler.

In addition, it’s worth noting that when in doubt, give the manufacturer a call to verify the parts list you plan to use. I cannot stress this enough. The more you plan out your build, the easier it is in the long run.

Muncie

PACE Performance (PN PAC- 1680-TK5) offers a good kit that includes virtually everything you need. While they say this kit is good up to 500 hp, a kit is available for horsepower up to the 600 range (PN PAC-1680-TK6). PACE requires that you specify what spline shaft you have, but that’s a given, right? The kits typically include a QuickTime SFI LS 4-speed bellhousing, Ram LS steel SFI flywheel, Ram 12-inch clutch disk, ARP bolts, pilot bearing, Clutch fork pivot ball, and fork boot. For $1,260, it might be the best option for you. You have to provide the mechanical clutch linkage from the pedal to the throwout bearing, but that’s pretty standard.

If you have all the necessary parts but just need a bellhousing to convert your Muncie to an LS engine, QuickTime sells them (PN RM-6036) through various vendors.

Refer to the above-mentioned throwout bearing measurement procedure if you choose to run a hydraulic throwout bearing with your manual transmission.

TH400/TH350/700R4/200R4

You can certainly install/mate a classic transmission to your LS engine. There are many reasons to do it. Maybe you have half a dozen lying around your front yard or maybe because TH400s are stout and fairly plentiful. Whatever the reason, you certainly can make it happen with the appropriate spacer, bolts, and a few extra steps.

The major difference is that the LS engine is .400 inch shorter than a typical small-block. The other difference is that the upper right bolthole for the bellhousing is missing. Thankfully, the bolt pattern is the same so you are able to use the same transmission case.

The solution to the shorter length is to use a spacer that can be purchased at places such as Scoggin-Dickey (GM PN 12563532) and Chevrolet Performance. Jeg’s and Summit (Hughes PN HP3795) carry their own proprietary brands. You then need to purchase longer bolts to match the spacer (GM PN 11569956). The spacer is bolted to the crankshaft first, between the crankshaft and the flexplate; do it the other way around and you have problems. You also need a flat-faced GM flexplate (PN 12551367). This allows the starter to be engaged in the correct spot by moving it rearward that extra .400 inch (Hughes HP4004X).

Beware that not all flexplates and flywheels are the same. The 1955– 1986 crankshafts with a two-piece rear seal has a 3.58-inch bolt circle while the 1987 to present crankshafts with one-piece rear seals have a 3.00- inch bolt circle. The LS crankshafts that have one-piece rear seals have a 3.11-inch bolt circle.

I have heard that you can use the curved or beveled 4.8/5.3 and LS1-style flexplates. This requires ovaling out the torque converter mating holes to make it fit properly. I’m not too keen on this idea as it tampers with something that takes a lot of abuse. Nor can I verify that this is accurate, so it may be worth investigating more fully before diving in. In this setup, you have to use a spacer, but it goes between the flexplate and torque converter to fill that cavity.

The final option may be the easiest, but also the most costly. You can purchase an LS-specific torque converter for your older-style automatic transmission that eliminates the need for a spacer. Currently several companies make a version for your transmission; expect to pay $450 or more.

Crossmembers

A number of crossmembers are on the market, and any of them does just fine. There are different crossmembers for each style of transmission; the most popular is the T56 crossmember. It must be said that it helps to plan ahead and make sure that the headers and engine mounts work with the crossmember. Ask first, purchase second.

ATS

The most popular name in crossmember swaps is ATS. It’s a threepiece unit. This piece works well with the stock subframe as well as aftermarket ones. Of course, Speed Tech acquired ATS a number of years ago, so it’s only fitting that their subframe comes with a transmission crossmember flexible enough to fit just about every transmission.

G-Force

G-Force is a specialty company that makes a wide range of crossmembers for the first- and second generation F-Bodies. They have a solid reputation and make crossmembers for almost any transmission. They offer units for older transmissions such as the T10, TH400, TH350, 700R4, and even newer ones such as the T56, 4L60E, and 4L80E.

Hurst Drive Lines

Hurst Drive Lines has a wide variety of parts and price ranges for making the T56 or TKO-5-speed swap or addition. They sell entire kits that take care of everything you need such as the clutch, clutch hydraulics, tubular crossmember, electrical connectors, shifter knob, transmission, driveshaft, flywheel, bellhousing, and speedometer cables or wires. These kits can be had for the first- or second generation F-Body as well as a wide variety of others applications.

Here’s a version of a custom transmission crossmember that bolts in from the side rather than from the top. (Photo Courtesy Texas Speed & Performance)

The only downside I could find is that each component is not available individually; they only come as a kit. Still, when you purchase a complete kit such as this one, you know that it’s designed to work in concert with all the other pieces.

Stock Crossmember

Reusing the stock crossmember is entirely possible; the trick is to modify it to make it fit your swap. I’ve seen a few reworked stock crossmembers that work perfectly well. The center part of the crossmember needs to be cut out, then careful measurements need to be taken to see how far the drop should be. The driveline angle here is extremely important. A good rule is that the engine needs to be tipped back roughly 3 to 4 degrees and the rear end should be tipped upward about the same amount with no more than a 2-degree difference for typical street driving.

I recommend a thicker plate steel (between 1/8 and 1/4 inch) if you choose to modify your stock crossmember. As with everything the compromise is time versus money. Crossmembers are readily available so you may have to consider which is a better choice: your time or a couple of extra dollars and less effort.

Bellhousing

Regardless of what transmission you want to put behind your LS engine, chances are someone sells a bellhousing for it. QuickTime offers an SFI-certified bellhousing to bolt just about any trans behind an LS engine, including Tremecs, Richmonds, and all the popular GM automatics. Other companies offering transmission solutions are McLeod and Lakewood. If you’re stuffing a T56 six-speed behind your LS mill, the low-buck route is to just run an aluminum GM housing, and of course, newer GM automatics have the bell integrated into the transmission case.

Written by Eric McClellan and Posted with Permission of CarTechBooks

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Interestingly, the coolant system on the LS engine lineup is not entirely different from a Gen I Chevy small-block that was installed in most of these first- and secondgeneration F-Bodies. The LS has two major ports: One comes into the engine while the other moves hot coolant out of the engine and into the radiator. Thankfully General Motors did away with the reverse cooling LT engine that seemed more of an experiment than a wellthought-out system.

These are three typical water pumps. The one with the larger bells is the most versatile as it can be made to fit the F-Body and the Corvette-style balancers. (Photo Courtesy Street & Performance)

This tech tip is from the full book, SWAP LS ENGINES INTO CAMAROS & FIREBIRDS: 1967-1981.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

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Early F-Body cars run an openbottle cooling system. However, a closed pressurized cooling system with a closed overflow bottle provides higher pressure and much better cooling than a standard open system. In addition, the extra capacity of the bottle in a closed system offers more cooling. While you can use the stock system with an open overflow bottle, it doesn’t provide nearly the same cooling capacity as the modern closed system.

If you’re scrounging the junkyard, you can pluck this system from many late-model GM cars, including the Cadillac CTS-V.

When installing a closed pressurized system, the lower line should be integrated into the return heater hose. For an LS engine this is the most forward 3/4-inch nipple on the water pump housing. The vent hose from the cylinder head should be hooked to the small upper nipple on the bottle.

Radiator

Although you may be tempted to use the original radiator from your F-Body with your new LS engine, this is not the right move and does not meet your high-performance goals.

This is the lower hose on Mary Pozzi’s LS engine swap. Because LS swaps don’t have specific hoses for the various water pump outlets to the radiator, I had to take a few home from my local parts house for some trial fits. The original hose was about a foot longer but the center section fit perfectly and now it clears the idler arm mount. (Photo Courtesy Mary Pozzi)

While it could work, it won’t provide enough cooling capacity, particularly if you’re using your F-Body in competition. Therefore, I don’t know of anyone who has tried reusing an original radiator from the 1960s or 1970s. It’s simply not worth using an old-style radiator and risk damaging your engine. The cooling efficiency of the old-style radiators just isn’t what they are today with aluminum radiators being the norm. I highly recommend upgrading your radiator as cheap insurance to protect against heat in your engine. Newer radiators are vastly more efficient, lighter, and use more reliable components such as electric fans and have larger cooling capacity.

Small-Block Radiator

While you can use a small-block radiator on an LS swap, there is one major difference. The upper radiator hose needs to be routed to the driver’s side, which requires a custom application of the hose. The standard small-block radiator works exactly the same way as the LS specific radiators do, the difference is, you guessed it, the placement of the upper radiator hose.

Keeping in mind that the upper radiator hose is the “hot” side, pushing the hot engine coolant from the engine to the radiator to be cooled, the same approach must be taken regardless of which radiator you choose.

Mary and her crew had to trial fit the upper hose in the same manner as the lower hose. As the fitting for the water pump was a smaller diameter than that for the radiator neck, I used a reducer (available at parts stores) to get this hose working with the LS swap. (Photo Courtesy Mary Pozzi)

The old direct-fit aluminum radiator and SPAL fan combination was used to cool the old small-block. It worked just fine and would probably work with the new Mast LS3. However, I upgraded the entire car and I needed to ensure the engine had excellent cooling so the engine could run at its best and not overheat. Besides, I wanted to run the A/C and I didn’t think the old system could handle the cooling requirements.

This comparison of the new aluminum core support from AutoRad and a stock core support shows that the AutoRad is significantly bigger and lighter. All the factory holes are there so it’s a direct bolt in. Of course, this is a lot more work, but the results speak for themselves when I can blast the A/C and hit some very high RPM, all while the engine stays cool.

Here is a close-up of the thermostat housing and heater core passages. The large port is the lower radiator hose and the two smaller ones are for the heater core.

You might run into this problem as well, which kind of threw me for a loop. The articulation of the heater wasn’t enough to clear the control arm so I had to find a better solution to the problem. I ended up using a plastic elbow that reroutes the hoses.

Using an old coat hanger, I mocked up the basic shape of the radiator hose and this provided a sense for the required length of the hose. Obviously, it was a custom application.

After searching my local Napa Auto Parts store, I finally found the correct hose for this application. The bends on this hose matched fairly well and the inside diameter (ID) of the hose was close enough for my comfort. The AutoRad radiator puts the opening farther away on the passenger’s side than the stock LS location, so I had to do some research. I dug around the cooling hose bin for quite some time before I found the right hose. I performed the same basic procedure for the lower hose as well.

I’ve seen it done on a few cars that wanted to retain the stock small-block appearance and not give away the deadly secret underneath. This option might be for you, but remember it takes a bit of work to make it work properly and not look like a hack job.

LS Radiators

A myriad of aluminum cross-flow radiators are available for LS swaps into first- and second-generation F-Body chassis. The stock LS radiators have both inlet and outlet passages on the passenger’s side of the engine. While you can route hoses to the driver’s side of the engine, it’s difficult to package all the components when running non-stock hose routes. Thankfully, several companies, such as AutoRad, Flex-a-lite, AFCO, and Be Cool, offer high-capacity aluminum radiators for early F-Body swaps.

The stock LS radiator out of a fourth-generation F-Body car installs because the first-generation’s direct mounting to the core support, but it is different than the fourth-generation F-Body setup. You have to be a bit creative when mounting the radiator If you plan on running an LSspecific cross-flow radiator (and why wouldn’t you?), Goodyear makes a number of upper and lower radiator hoses that are compatible with an LS radiator, but you’re going to have to cut and fit to install them. Those part numbers are: Goodyear MH585 for the upper radiator hose and MH1235 for the lower hose. These part numbers may have been different in previous years and are not direct-fit hoses. In addition, they may be somewhat difficult to install and may take some muscle and trimming to get them in place.

My 11 ⁄2-inch ID hose worked out quite well. Looks like a factory part after I trimmed it to fit better. For those with this configuration, the upper hose was PN 8919 from Napa Auto Parts.

Here’s a side shot of the hose. Notice the clearance with the LS engine and no need for a clutch and fan blade assembly.

The upper and lower radiator hoses now need to be run. This typically isn’t an off-the-shelf part so I have to come up with a better idea.

While you are at the parts store rummaging through the radiator hoses for the right one, it is helpful to know that the inside diameter (ID) of the hose you’re looking for is 11 ⁄2 inches. This is for both upper and lower sizes. You might have to cut and adjust a bit on each hose to make it fit just right but if done correctly, it looks factory.

AutoRad

This radiator and fan combo boasts a 40-percent surface area gain over a stock radiator and a 20- percent surface area gain for even the best radiators on the market, which is impressive. I want the capability of blasting the A/C while hitting the corners hard at the track. A radiator that can keep it all under control is a big bonus to us. In addition, if I choose to upgrade to even more power in the future, this unit is up to the task and one less thing for me to worry about.

To install this radiator, the core support needs to be replaced. If yours looked as butchered as mine did, replacing it is probably a wise thing to do. Another reason I went this route is that the stock LS radiators typically have a sandwiched design; the two side-headers are made of plastic and are joined to aluminum cores. This is typically the weak spot in a modern radiator and after repeated heating and cooling cycles those joints wear down and eventually leak and need replacing.

The AutoRad radiator has in and out ports for the radiator hoses on the same side of the radiator; this is different than a typical GM setup. The radiator also came with two electric fans each requiring 18 amps of power. The Mast wiring system is a bit different, so it works with one fan. However, I was able to connect both fans as the Mast harness has a 40-amp relay and can handle the power of both fans at once. A typical LS system has a relay for each fan. You may have to modify yours to fit your application.

The radiator and fan combo has been installed just like the stock one would have been (with two on each side of the radiator). The supplied catch can for the radiator mounts on the cap side with the same two bolts that hold it in place. The fans came with a pre-made wiring harness. Because the Mast harness comes with wires for electric fans (much like the stock ECM), hook up was a breeze by simply splicing the ECM wires into the fan harness

With all the options available from AutoRad, I opted for the dual fan setup and the A/C condenser already mocked up into place. AutoRad throws in all the hardware you need so this really was a no-brainer.

This tech tip is from the full book, SWAP LS ENGINES INTO CAMAROS & FIREBIRDS: 1967-1981.

For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT THIS BOOK HERE

SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://www.lsenginediy.com/firebird-camaro-ls-swap-cooling-system-guide/

Radiator Hose Location

On an LS engine, both radiator hoses route from the passenger’s side of the engine. The accessories can interfere with connecting the upper radiator for certain engines and setups for folks who want to run a stock first- or second-generation F-Body radiator or in applications where a turbo or supercharger has been added. Dropping in a dual-pass crossflow radiator resolves this problem by connecting both hoses on the passenger’s side of the engine.

An additional benefit to dual pass radiators is that they keep the coolant in the radiator longer. This allows the fan to remove more heat, and it increases the ability of the radiator to cool more efficiently. Every LS engine is equipped with a 195-degree thermostat. The major difference is that the outlet for the thermostat is not in its typical position directly on top of the intake as with the small-block. The engine must retain the thermostat because it’s a direct flow-through design, so you don’t want to remove it and damage the engine.

The new core support differs in size and the way it mounts to the front grille and latch support. A slot is on the inside of the core support; these two bolts need to thread through before you can attach the radiator. The new core support replaces the stock support and mounts in the exact same way using the stock bolt locations.

The steam tube comes off the head and needs to be correctly routed. This owner tapped the water pump and took the steam tube directly to it. You can do something similar or just go to the radiator with standard coolant tubing as I did.

The steam line is behind the power steering pump and reservoir on the driver’s side of the engine. It needs to be routed back into the cooling system. It can be done in many ways, but I routed mine to the steam vent tube on the AutoRad radiator with standard coolant hose and hose clamps.

The correct 3/4-inch elbow made it bend out of the way. I found this piece at the local hardware store for less than $3. I have since learned that you can find pre-bent coolant tubing at the local parts store. This is a much better alternative because it removes many of the clamps required with a plastic elbow. I don’t prefer this method as it creates more areas for problems and leaks, but sometimes it’s a necessary evil to finish a job.

The LS engine doesn’t run its coolant through the intake manifold like previous Chevrolet engines did so there are some subtle differences in operation. Many swappers simply drill and tap the water pump and direct the flow straight into the water pump and back into cooling system. This works well and I have seen no problems from many different installs.

Another way to do it is to put an inline adapter from the upper radiator hose or possibly the heater hose. Either way works equally well. The real question becomes, “How much work am I willing to put in?”

A number of radiators have a steam vent bung that comes already attached to the radiator if you choose to use it; otherwise put a plug in it. This is by far the easiest conversion method, but also the least cleanlooking way to install it.

Coolant Steam Line

Another unique feature of the LS cooling system and the LS system itself is that it uses a coolant steam line. The coolant steam line is designed to vent excess air pockets from the coolant system. Air is the enemy of any proper cooling system and this system does a nice job of removing unwanted air pockets without a lot of mess. When performing a swap, you need to route and connect the tube to the upper radiator hose. This line must be hooked up or the engine could overheat.

Heater Outlets

The heater hose outlets are pretty consistent from car to car. Even the new-style C6 Corvette and the first-gen F-Body share the same heater hose size and routing plan. The LS engine locates the heater hose outlets directly behind the thermostat housing.

You may have to purchase a truck-style thermostat cover. It allows for a better angle of attack on the lower radiator hose. (Photo Courtesy Street & Performance)

When looking direct at the two plugs from the passenger’s side, the rear-most port accepts a 5/8-inch heater hose and has a matching port on the heater core, this is the “in” port as hot coolant passes from the engine to the heater core. The forward-most facing port is a 3/4- inch heater hose and is the “out,” or return, side of the system. The heater core returns the cooled coolant from the heater core back into the engine.

Coolant Temperature Sensor

For some reason my PCM and gauge cluster did not like to play well together so I had come up with another solution to gauge the coolant temperature rather than the typical places. I found a coolant adapter from Auto Meter that taps into the feed line of the heater hose and uses a 1/8 NPT fitting for the coolant temperature sensor.

Remember to ground this piece or your gauge reads zero.

Electric Fan

Electric fans come in numerous shapes and sizes. The stock Corvette and F-Body LS engine typically comes with two fans: the main lowspeed fan and one that comes on at high speed when the engine requires the extra cooling. You might want the dual-fan setup if you’re on a budget because it’s a proven system that works well. The dual fan setup can be had from junkyards fairly cheaply.

If your wiring harness doesn’t have any relays, you have to add a couple to precisely match the situation. Relays are a great way to power something off the battery without causing any serious drain and provides safety by allowing power to be turned on only when truly needed. If you choose to use a Gen IV style ECM, you have some extra wiring to complete the pulse-width modulation system. This is the same technology used in the fuel pump, essentially only going as fast as it needs to on short electrical pulses. Since this is the aberrant situation rather than the norm, I stick with the on-off style of fans.

A lot of aftermarket kits are available today. AFCO, BECOOL, and Ron Davis are just a few names in the market now. I’m sure others complete the job adequately. All of them have a variety of setups available that include bare radiators all the way up to full kits with fans, shrouds, and wiring harnesses. It’s really up to you how far you want to go with it. If you’re planning on running some big power, you might want to look toward Ron Davis or AutoRad for your cooling needs.

The fans I had on the AutoRad system use a dual 18-amp fan system. Because my Mast ECM is only programmed to work with one fan, I simply hooked up the fan wires to both fans at once. The Mast ECM is designed with a 40-amp breaker, so I had plenty of power to spare.

PCV System

The LS PCV (positive crankcase ventilation) system is a little different than the standard system that is on a typical small-block. The system on the LS engine has three ports that need to be routed correctly. The LS engine, like most other engines, makes positive pressure when in operation. These pressures need to be dealt with or the engine starts leaking profusely through the weakest part of the engine, typically the gaskets. The PCV system allows the engine to expel those gases (known as “blowby”) through three ports: one on each valve cover, and one on the front port coming off the intake valley. Do not block these ports or modify them as they provide crucial venting for your shiny new engine. The last thing you want is a sick, weeping, and puking pile of aluminum.

If you choose to order a crate engine from Chevrolet Performance or a GM dealership, be aware that their instructions are slightly different but that both work.

Installation

The strict Chevrolet Performance instructions say that you should connect the two foul side ports to the intake manifold and be exposed to vacuum at idle. These two ports are the valley port and the driver-side valve cover port. The passenger-side port should be connected to a clean air source such as the air cleaner. If you chose to use a MAF sensor on your car, the passenger-side port should be mounted between the MAF and the throttle body, typically on the intake tube. If the port is connected before the MAF, it confuses the sensor and possibly throws an erroneous code.

Chad Vancura made my oil catch can. You can purchase one from an outlet catalog, such as Jegs, Summit, and others, but I wanted mine to be a very specific size to match my application. I had a small area to work with so the only real option I had was to fabricate one to meet specific needs.

This port on the oil valley needs to be hooked up to a vacuum source. I ended up looping this up to the intake. One note of caution: It’s wise to use a catch can with this look primarily because any oil that gets puked out of the engine just gets sucked right into the intake, and that’s never a good thing

I set up this system as simply as you would want to. I routed both valve cover ports to a T-fitting with 3/8-inch vacuum line and then a single line to a small and unobtrusive catch can to catch any excess blowby. The can is topped with an air cleaner so that any return air or oil isn’t contaminated. The valley port is connected to a vacuum source, this can be virtually any vacuum source, such as a brake booster, but I chose the shortest and easiest route, which is directly to the intake pipe right before the throttle body.

Written by Eric McClellan and Posted with Permission of CarTechBooks

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