Often the exhaust portion of a build is left to the very end when everything is bolted up; it’s often quite literally an afterthought. As I stated in Chapter 2, a sound strategy is to select the engine mounts, transmission crossmember, headers, and related parts as a kit. The header routing and clearance of the brake booster, steering rod, and other components are common problems. You have to take all of the components into account when making a decision.
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:
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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.
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 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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