How to Choose the Best Cam & Lifters for a Gen IV LS-Engine • LS Engine DIY

Today’s performance aftermarket offers a wide selection of camshaft profiles for enhanced performance, from street-mild to all-out racing competition. While factory camshafts all utilize hydraulic roller lifters, the performance aftermarket offers lifter application in both hydraulic and solid designs. One very significant feature of the LS cam design is its cylinder firing order. While the Gen I small-block Chevy cam firing order is 1-8-4-3-6-5-7-2, the LS firing order was changed to 1-8-7-2-6-5-4-3 to enhance power. This is discussed later in this chapter, as are the theory and function of factory variable valve timing and displacement on demand, two different approaches that GM employed to improve fuel economy.

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Camshaft Terminology

A brief explanation of camshaft terminology and specifications follows here, citing information provided by Lunati as the examples.

Nose

The camshaft lobe nose is the highest point that provides maximum valve lift, between the opening and closing ramps of the lobe.

How to Choose the Best Cam & Lifters for a Gen IV LS-Engine

High-performance roller lifters are available individually to use with OEM plastic lifter guides or as tie-bar-connected pairs that eliminate the need for the plastic lifter guides. The only downside of using tie-bar roller lifters is that during a camshaft change, the lifters must be removed in order to reach the cam. The plastic lifter guides allow you to pop the lifters up and away from the cam lobes without the need to remove the lifters. With the rocker arms and pushrods removed, by rotating the crankshaft twice, the lifters are pushed up into the “locking” position where they are slightly gripped by the guides, holding the lifters up and out of the way. However, not having that feature is a small price to pay for the advantage of the extremely durable tie-bar roller lifters that are available in today’s aftermarket.

Base Circle

The base circle, also referred to as the lobe heel, is the lowest point of the lobe. This is the point at which the valve is in the fully closed position and the point at which valve lash adjustments are made. When measuring for a custom pushrod length, the lifter is at its lowest point, where pushrod length is measured between the lift cup and rocker arm.

Symmetrical Lobes

Lobes that are symmetric are machined with mirror-image/identical opening and closing ramps on each side of the lobe.

Asymmetrical Lobes

Asymmetrical lobes are machined differently at the opening versus closing ramps. Typically, an asymmetric lobe provides a faster/higher-velocity opening ramp and a slower-velocity closing ramp. This allows the valve to close with less impact force.

Lift

Lift refers to how far the valve is raised from its seat when completely open. Note that lobe lift and valve lift differ. Lobe lift refers to the distance from the base circle to the lobe peak. Valve lift considers both lobe lift and rocker arm ratio. Valve lift is easily calculated by simply multiplying the lobe lift by the rocker arm ratio. For example, if the cam features a lobe lift of .377 inch and is coupled with a rocker arm ratio of 1.7:1, the effective valve lift is .641 inch. If a 1.8:1 rocker arm ratio is used with the same cam, the effective valve lift is 0.678 inch.

The intake and exhaust valves need to open to let air/fuel in and exhaust out of the cylinders. Opening the valves quicker and farther usually will increase engine output. Increasing valve lift without increasing duration can yield more power without much change to the nature of the power curve. However, an increase in valve lift almost always is accompanied by an increase in duration because the lobe ramps are limited in their shape, which is directly related to the type of lifters being used, such as flat tappet or roller.

While many cams may feature more lift on the exhaust side than the intake side, this is primarily done to help compensate for less-than-efficient exhaust ports. Today’s high-performance LS heads feature improved flow, so you’ll see cams available with more intake lift to help draw more mixture into the chambers.

Duration

Duration represents the angle in crankshaft degrees that the valve stays off its seat during the lifting cycle of the camshaft lobe. Increasing duration keeps the valve open longer and can increase high-RPM power. This also increases the RPM range where the engine produces power. Increasing duration without a change in the lobe separation angle (LSA) will result in increased valve overlap.

When you view cam specifications, advertised duration and duration at .050 inch will be listed. This is the angle in crankshaft degrees that the lifter is lifted more than a predetermined amount off its seat. Because advertised duration can vary depending on cam makers, based on a predetermined point chosen by the cam maker, an industry standard of listing duration at .050 inch allows direct comparison of duration across all brands. Duration at .050 is a measurement of the movement of the lifter, in crankshaft degrees, from the point where it first lifts .050 inch from the base circle on the opening ramp side of the cam lobe to the point where it ends up being .050 inch from the base circle on the closing ramp’s side of the lobe. This is the industry standard and is a good value to use to compare camshafts from different manufacturers.

Lobe Separation

Lobe separation, referred to as LSA, is the angle in camshaft degrees between the maximum lift points of the intake and exhaust valves. Lobe separation affects valve overlap, which affects the nature of the power curve, idle quality, and idle vacuum. LSA can be measured using a dial indicator and a degree wheel, but it is usually calculated by dividing the sum of the intake centerline and the exhaust centerline by two. In very general terms, a low LSA, let’s say from 106 to 108 degrees, for example, may produce a rougher idle and lower engine vacuum at idle and move the power band to the mid-to-high RPM range. A larger LSA, let’s say in the 112- to 114-degree range, would produce a smoother idle and more engine vacuum at idle and would move the torque curve to the lower RPM range for quicker response and a broader RPM band.

Overlap

Overlap refers to the angle in crankshaft degrees that both the intake and exhaust valves are open. This occurs at the end of the exhaust stroke and the beginning of the intake stroke. Increasing lift or duration and/or decreasing lobe separation increases overlap. At high engine speeds, valve overlap allows the rush of exhaust gasses out of the exhaust valve to help pull the fresh air/fuel mixture into the cylinder through the intake valve. Increased engine speed enhances this effect. Increasing overlap increases top-end power and reduces low-speed power and idle quality. Overlap can be calculated by adding the exhaust closing and the intake opening points. For example, a camshaft with an exhaust closing point at 4 degrees after top dead center (ATDC) and an intake opening point at 8 degrees before top dead center (BTDC) has 12 degrees of overlap. Decreasing the lobe separation by only a few degrees can have a huge effect on the overlap area.

Camshaft lobe separation, referred to as LSA, is the angle in camshaft degrees between the maximum lift points of the intake and exhaust valves. Lobe separation affects valve overlap, which affects the nature of the power curve, idle quality, and idle vacuum. LSA can be measured using a dial indicator and a degree wheel, but it is usually calculated by dividing the sum of the intake centerline and the exhaust centerline by two. (Photo Courtesy Lunati)

The camshaft centerline is the point halfway between the intake and exhaust centerlines. The intake centerline is the highest point of lift on the intake lobe, expressed in crankshaft degrees after top dead center (ATDC). The exhaust centerline is the highest lift point on the exhaust lobe, expressed in crankshaft degrees before top dead center (BTDC). (Photo Courtesy Lunati)

Centerline

The intake centerline is the highest point of lift on the intake lobe, expressed in crankshaft degrees after top dead center (ATDC). The exhaust centerline is the highest lift point on the exhaust lobe, expressed in crankshaft degrees before top dead center (BTDC). The camshaft centerline is the point halfway between the intake and exhaust centerlines.

Cam Advance and Retard

Advancing or retarding the camshaft moves the engine’s torque band around the RPM scale by moving the valve events farther ahead of or behind the movement of the piston. Typically, a racer will experiment with advancing or retarding a camshaft from the “straight up” location. In general terms, advancing a cam will improve low-end power and response, while retarding a cam biases the torque band to favor high-end power.

Advancing or retarding the camshaft moves the engine’s torque band around the RPM scale by moving the valve events farther ahead or behind the movement of the piston. With the use of an adjustable aftermarket cam timing gear set, you’re able to advance the cam to improve low-end power and response, or retard cam timing in favor of high-end power.

Advancing the cam position begins the intake event sooner, opens the intake sooner, builds more low-end torque, decreases piston-to-intake valve clearance, and increases piston-to-exhaust valve clearance. Conversely, retarding the cam position delays the intake event and opens the intake valve later, builds more high-end power, increases piston-to-intake valve clearance, and decreases piston-to-exhaust valve clearance.

Factory Camshafts

Listed here are specifications for stock production camshafts in Gen IV engines. All factory LS engines feature hydraulic roller lifters and roller camshafts.

Active Fuel Management (AFM)

Some LS engines feature active fuel management (AFM) involving either displacement on demand (DOD) or variable valve timing (VVT). DOD essentially shuts off specific cylinders via oil-pressure/ spring-controlled/spring-assist special lifters when engine demand is low. VVT works by adjusting valve timing depending on engine RPM: retarding valve timing at high RPM and advancing timing at low RPM. The goal of either system is, in theory, to gain fuel economy. In reality, for a high-performance build, it’s best to delete these systems to obtain maximum power potential. To delete an active fuel management system and take advantage of a high-performance aftermarket camshaft, active fuel management delete kits are readily available, both for DOD and VVT systems.

DOD System

A DOD system disables half of the cylinders (1-4-6-7) under cruising or low-load conditions by collapsing the lifters in those cylinder locations and by cutting the spark for the same cylinders. When demand increases, the lifters are activated and “normal” lifter performance returns. The system is operated by the engine control unit (ECU) and four solenoids located in the upper valley, attached to the valley plate assembly known as a lifter lower manifold assembly (LLMA). The solenoids provide pressurized oil to the special roller lifters. The system is tuned to a specific factory camshaft, with the lobe profiles between the AFM and non-AFM cylinders different because of different valve lash requirements. Upgrading to a high-performance camshaft requires not only the new camshaft, but also replacing the special AFM lifters and lifter retainers, replacing the valley cover, eliminating the four solenoids, and plugging the oil delivery towers in the valley. In addition, the ECU must be reflashed/recalibrated. Plugging the oil towers is outlined in chapter 2.

DOD lifters feature “assist” springs. When the engine is under light load, the ECU signals a cutoff of oil supply to the select DOD lifters, allowing those lifters to collapse so that the intake and exhaust valves in the DOD locations close, shutting off firing to the four select cylinders. The spring on the DOD lifters maintains just enough pressure to the pushrod to prevent the pushrods from loosening and falling out. The DOD lifters feature a notched anti-rotation design that differs from standard LS lifters, requiring a different DOD-specific plastic roller guide tray.

While DOD or VVT factory cams might feature a single-bolt cam gear and cam, most aftermarket performance cams feature a three-bolt design. Because of this, part of deleting AFM involves obtaining a new 4X cam gear that features a three-bolt design.

DOD roller lifters retain the same .750-inch-diameter roller as standard LS roller lifters.

Using a DOD camshaft along with a DOD delete kit won’t work; it will result in a misfiring engine. A non-DOD camshaft is required.

VVT System

The VVT AFM system operates by the ECU monitoring valve timing through the camshaft position sensor. The ECU sends a signal to a solenoid that’s mounted to the timing cover. The solenoid controls oil flow through a control valve built into the single camshaft bolt, operating a camshaft phaser actuator on the timing cover that rotates to advance or retard the camshaft.

A DOD delete kit, required for installing a non-DOD camshaft, includes a set of standard LS, non-DOD lifters, lifter guides, valley cover, new OEM-style head bolts, head gaskets, PVC hose, and PCV plug. This example is Trick Flow’s PN 30678503. (Photo Courtesy Trick Flow Specialties)

VVT was first employed in select 6.0L and 6.2L LS engines. The front-mounted actuator controls the amount of intake and exhaust valve overlap. The engine’s ECU commands the actuator to advance or retard the camshaft. The VVT camshaft features an internal oil passage that sends oil to the actuator. The actuator uses oil hydraulic pressure to change the camshaft timing. An actuator magnet is mounted to the front face of the timing cover, connected to 12 volts. When the solenoid is energized, the electromagnetic force on the magnet positions the spool valve of the solenoid. During engine operation, the ECU adjusts cam timing within a range of about 7 degrees of advance to about 55 degrees of retard.

An example of a VVT delete kit from Trick Flow Specialties, PN 30678505. A new timing cover (type LS2/LS3) featuring the camshaft phaser actuator is included to replace the VVT cover. (Photo Courtesy Trick Flow Specialties)

The VVT system features a single-bolt camshaft. The cam bolt incorporates an internal spool valve with an internal check ball and filter. Pressurized oil that runs through the cam is sent through the spool valve to control the timing actuator. The valve spool directs oil out of advance/retard oil ports to the actuator.

The VVT system doesn’t like high-performance cams, which limit valve lift and duration. Also, higher valve spring pressures required for a high-performance cam can overwhelm the actuator. Just get rid of the VVT. Deleting a VVT system is slightly less intrusive or complex than performing a DOD delete. Deleting VVT only requires swapping out the cam gear, timing cover, cam position sensor, and cam gear bolts, in addition to the performance camshaft of choice. The ECU will also need to be recalibrated for non-VVT operation. A VVT delete kit will be necessary when removing the active fuel management VVT system from a Gen IV engine.

The nose of the VVT cam bolt/spool valve features a face protrusion that contacts the magnet of the timing cover cam position actuator.

The cam position actuator magnet mounts to the exterior of the timing cover. The power connector is positioned at about seven o’clock when mounted.

The rear of the cam position actuator magnet places the electromagnet facing the VVT cam bolt/spool valve nose.

Typical delete kits include a three-bolt 4X cam timing gear, timing chain damper, LS2/LS3 timing cover, eight timing cover bolts, timing cover gasket, timing cover front seal, cam position sensor, cam sensor harness bracket, cam sensor harness, three ARP camshaft bolts, and water pump gaskets. The cam sensor features a three-pin connector, as opposed to the five-pin VVT connector. To use the new sensor, you need to remove the wires from the three-pin connector and reuse theoriginal five-pin connector, or you can simply swap the cam sensor from the existing VVT cover to the new cover. Some kits also include a new camshaft retainer plate and crankshaft bolt.

A VVT camshaft features an internal oil passage that allows pressurized oil to be delivered to the cam bolt/spool valve. The majority of aftermarket performance camshafts feature a three-bolt design, so a three-bolt cam timing sprocket is needed to accommodate the new performance cam.

Gen IV LS3 and LS7 engine packages offer tremendous power potential due to the larger displacement and superior-flowing cylinder heads, but the weak spot involves the camshaft. Factory cams are designed to provide a compromise between power, torque, idle quality, and fuel mileage. Substantial power gains can be had by simply changing cam profile, by as much as a whopping 70 hp. Keep in mind that factory valve springs are mated to the factory cams. When increasing valve lift and extending the RPM range, higher-rated valve springs must accompany a cam swap.

As far as AFM systems are concerned, whether DOD or VVT, just eliminate this nonsense. Each system involves added components that increase the potential for parts failures, and they limit performance potential. If you’re after optimum performance for the street or track, just delete the AFM and get back to basics that allow you to take advantage of LS power potential. However, if your primary goal is to improve fuel economy instead of maximizing power, just buy a Prius hybrid and blend into the crowd of non-car folks.

Intake and Exhaust Difference

While some cam makers choose to use the same lift at intake and exhaust locations, some prefer to use a bit less lift at the exhaust to promote better exhaust scavenging. Exhaust valves are smaller than intake valves, so we have less exhaust volume than intake volume. Exhaust exits the cylinder head based on piston displacement, cylinder pressure, and header pull-out scavenging. By running less lift at the exhaust valve than at the intake, the exhaust can speed up, creating more vacuum and exiting faster. If exhaust volume is too large, it can reverse, which is detrimental to power.

The use of electronic fuel injection (EFI) in LS engine applications is obviously commonplace, but if you decide to run a carburetor setup, you have two basic choices in terms of duration and lobe separation. If you run a carburetor with a cam that has a shorter duration and tighter lobe separation, the engine will be “snappier,” building peak power more quickly but also losing it more quickly. However, by running a longer duration and wider lobe separation, you broaden the power curve for better midrange and top end.

Camshaft Firing Order

In certain racing applications, a special firing order camshaft (SFO) can be used as a tuning aid, allowing the competition engine builder to further address combustion heat and crankshaft disturbance (harmonic) issues. The goal in changing firing order is to create a smoother-running engine, more-even fuel distribution, and enhanced crankshaft and main bearing durability. In the process, horsepower gains may be achieved as well (no guarantees here, but in most cases a slight power increase does result).

The traditional firing order for Chevy small-block and big-block engines has always been 1-8-4-3-6-5-72, which is determined by the crankshaft rod pin layout. Each cylinder has a “companion” in the firing order. This companion cylinder will reach top dead center (TDC) at the same time as its counterpart, one on the power stroke and one on the exhaust stroke. These cylinders are paired as 1 and 6, 2 and 3, 4 and 7, and 5 and 8; these can be interchanged in the firing order without altering the crankshaft. Some builders report seeing no power improvement, and other builders claim to have achieved power gains by switching cylinders 4 and 7 to create a new firing order of 1-8-7-3-6-5-4-2. This can enhance fuel distribution, especially in open plenum–type intake manifolds, and reportedly can result in an added 5 to 10 hp.

For example, Pro Stock drag engines typically take advantage of a 4/7 swap. Swapping number-7 and number-4 cylinders in the firing order eliminates the fuel distribution and heat problems caused by cylinders number-5 and number-7 firing in succession. With the revised firing order, the two end cylinders do not have to fight for fuel from the manifold plenum. The result, in many cases, is a measurable power increase(typically 8 to 10 hp) and a smoother, cooler-running engine.

Playing with special firing orders isn’t limited to the advanced race engine builder. General Motors adopted a special firing order in its Gen III and IV LS engine series, which feature a 4/7 and 2/3 swap for the same reasons: to smooth out the harmonics in the pursuit of greater engine durability and to potentially generate more power. In the early development of the LS, GM’s analysis showed that main journal number-4 had peak leads that were significantly higher than in main number-2. By changing the firing order to 1-8-7-2-6-5-4-3, the peak loading on main number-4 was reduced and the peak loading on number-2 went up. Overall, the loading among the main journal locations showed improved balance. In turn, the oil film between main bearings and main journals was better balanced at all main locations.

The primary reason to alter cylinder firing order is to achieve a smoother-running engine that delivers a more lineal acceleration ramp with less harmonic effect and crank deflection on the crankshaft and its main bearings. The goal of swapping firing order positions is to reduce crankshaft harmonic effects caused by two adjacent cylinders firing in succession (companion cylinders). By strategically relocating these companions, it’s possible for the engine to idle and run smoother, to reduce isolated hot spots (cylinder-to-adjacent-cylinder walls), and to even out fuel distribution, primarily in applications that feature a single-plane intake manifold, and even more noticeably in tunnel ram intake manifold applications.

With a fuel injection setup, a lean cylinder can be richened (via the engine controller) to eliminate detonation, so firing order changes may not be as beneficial in an injected engine because fuel is delivered on an individual-cylinder basis. However, the LS firing order takes advantage of a 7/4 and 3/2 swap as an additional tuning aid, to produce an even smoother acceleration profile and to benefit crank and bearing life.

Hydraulic or Solid

Hydraulic camshafts are designed to use hydraulic roller lifters. Once valve lash is set, no further lash adjustments should be needed. Hydraulic lifters provide smooth response and the hydraulic valve inside the lifter compensates for harmonics and for thermal expansion and contraction and dampens shock to the cam and valvetrain, making them ideal for street use.

Solid roller cams and lifters are intended for maximum performance and allow the use of more aggressive cam profiles. Solid cam and lifter combinations also better withstand higher valve spring pressures. When valve lash is set to the tight side of around .010 to .012 inch, solids also offer superior throttle response. The limitations, or drawbacks, if you will, involved with solid lifters include a higher price tag; the need for periodic valve lash adjustment due to variations of heat and thermal dynamics; increased noise, especially during cold starts; and poor suitability for extended low-RPM operation. Yes, a solid roller cam can be used in street applications, but routine checking and adjustment of valve lash is mandatory, something that many street enthusiasts may not be willing to perform. In short, for a street application, go with hydraulic. For racing use, go with solids. Aftermarket cam makers offer a wide range of profiles for LS applications in both hydraulic and solid formats.

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Examples of extreme-duty race-level lifters include those offered by Comp, Lunati, Morel, and Gatorman (formerly Crane, available through Howards Cams), and for extreme-duty solid rollers, a brand called BAM.

Cam Gears

All Gen IV camshaft gears feature a 4X reluctor lug pickup design, for front-mounted camshaft position sensor location. On Gen III engines the camshaft position sensor was mounted at the top rear of the block. This is an easy way to identify a Gen III versus a Gen IV engine.

Gen IV cam gears feature a three-bolt hole pattern for cam attachment except the 2007 LS2 and 2008 LS3 and LS9, which feature a single-bolt mount.

The three-bolt 4X cam gear is designed for a front-of-block-mounted camshaft position sensor. Note the timing notch, which aligns at six o’clock in relation to the crank gear at twelve o’clock, with the number-1 piston at TDC with the number-1 valves closed. All LS cam gears feature this timing reference notch.

Aftermarket performance cam makers offer LS cam kits that include either OEM-style LS roller lifters, as shown here, or lifters that are tied together in pairs via a link bar. The LS lifters that copy the factory lifter dimensions and basic design allow the use of the original plastic lifter guides, whereas linked lifters eliminate the need for the plastic guides. Aftermarket cam makers such as Crane, Lunati, Comp, Bullet, and others offer an extremely wide selection of cam profiles for any LS application, from mild street to extreme race applications.

All Gen IV cam gears mount to the camshaft with a three-bolt attachment. The exceptions are the 2007 LS2 and 2008 and later LS3 and LS9 applications that feature a single center-bolt gear-to-cam mounting. However, aftermarket cams and cam gears are available for LS3 and LS9 applications that feature a three-bolt design.

The three-bolt Gen IV cam gear, featuring a 4X lug for Gen IV camshaft position sensor pickup, is available as PN 12586481 (shown at left). Three-bolt 1X cam gears, PN 12576407, were used only in 2005 LS2 Corvette and 2005–2006 LS2 GTO/SSR applications.

All Gen IV engines feature the camshaft position sensor up front, at the timing cover. The camshaft position sensor part number for Gen IV 4X cam gears is 12591720. This cam position sensor applies to LS2, LS7, LS3, and LS9 applications. If you need a camshaft position sensor harness (doing a swap, etc.), the GM part number is 12627501.

An easy way to identify a Gen III versus a Gen IV is the location of the camshaft position sensor. If the sensor is mounted at the timing cover, it’s a Gen IV engine.

Lifters and Lifter Guides

In an LS engine build, you have two choices of lifters: OEM or aftermarket. OEM-style lifters must be guided within an OEM plastic guide. Aftermarket performance lifters are connected in pairs via a pivoting tie-bar link.

Factory plastic lifter guides provide a register feature: the lifters have opposing flats on the upper body that register into flats in the plastic guides. This style is certainly adequate to maintain the lifter roller bearings in plane with the cam lobes. While flat-tappet lifters are designed to rotate in their bores during operation, roller lifters must remain in a fixed plane to allow the roller bearings to roll against the cam lobes. If the lifter rotates a bit, the rollers may tend to skip and chatter along with cam lobes. A superior approach is to use high-quality aftermarket roller lifters that are tied together in pairs with a pivoting link bar. This style provides a much more precise design that keeps the lifter rollers in plane with the cam lobes.

Over time, age and wear to the plastic guides may allow the lifters to slightly rotate out of plane; perhaps not enough to destroy a cam but enough to reduce efficiency and the long-term durability of both the lifter roller and the cam lobe. For maximum performance and durability, linked tie-bar lifters are a superior choice, especially when you’re chasing maximum performance and sustained high engine speeds. In short, if you’re planning to slam the engine for all it’s worth, get rid of the factory plastic guides and factory-style lifters and upgrade to tie-bar roller lifters.

If you’re using the OEM plastic lifter guides, be aware that excess oil tends to puddle at the floor of each lifter’s location. For faster oil drainback, drill about a 5/16-inch diameter hole at the outboard side of the guide, just above the floor at each lifter location. The outboard side is the one that faces the exhaust side of the engine. After drilling the holes, carefully deburr to remove any plastic fragments, then wash and clean to make sure that the guide is free of debris.

If you’re using aftermarket roller lifters that are connected in pairs with a tie bar, you have no need for the OEM plastic lifter guides. The purpose of using OEM guides or tie-bar lifters is to maintain the lifter rollers in plane with the camshaft lobes. Unlike flat-tappet lifters that are designed to rotate during operation, roller lifters must be locked in plane to prevent rotation, allowing the lifter roller tips to roll against the lobes. If a roller lifter rotates in its bore, the lifter will crash and scrub against the lobe, resulting in very quick and catastrophic damage to both the lifter and cam lobe.

CAMSHAFTS AND LIFTERS

Note that due to the design of the LS block and cylinder heads, lifters may be installed or removed only with the cylinder heads and head gaskets removed. Unlike early generation small-block engines that allow lifter access by removing the intake manifold, gaining access to LS lifters requires removal of the heads and head gaskets.

When securing the OEM plastic lifter guides, the OEM 6-mm x 1.0 bolts must be used; they feature a shoulder under the bolt head that properly registers the lifter guide to the block. These bolts are tightened at 106 in-lbs. Applying a drop of Loctite 242 blue thread locker isn’t a bad idea.

Lifters guides, also referred to as lifter buckets or lifter trays, tend to collect excess oil at the outboard sides. It’s a good idea to drill a 5/16-inch hole at the lower outboard side of each bank to allow better drainback.

While factory LS cams may feature a single-bolt or three-bolt connection of the cam gear to the cam, the majority of aftermarket performance cams feature the three-bolt design.

Pictured here is a factory roller lifter from a 5.3L engine (left) and an aftermarket roller lifter for the same application. The performance lifter features a more robust roller bearing and heavy-duty bearing axle. Also notice the difference in overall length.

Install the camshaft retainer plate with new screws. ARP retainer plate screws are highly recommended. Apply a drop of medium-strength thread locker to each screw’s threads, and tighten to 18 ft-lbs.

Many performance builders prefer bronze lifter bushings, which provide superior lubricity for the lifter bodies. Installation requires overboring the lifter bores, press-fitting the bronze bushings, and machining the bushing inside diameters to provide lifter bore oil clearance, which is usually in the .0015-inch to .0018-inch range. Machining the lifter bores and sizing the bushing inside diameters should not be performed with abrasive honing stones, as this may result in inconsistent inside diameters along the length of the bushings. The preferred method is to machine with the appropriate cutters, either using a specialty fixture to obtain the correct geometry and bore angle or with the use of a CNC-machining center. This photo shows bronze lifter bushings installed in a World Products Motown II LS block, but the same practice applies to conventional LS blocks.

An aftermarket lifter may feature a deeper pushrod cup location. This is one more example of why it’s important to measure for pushrod length instead of assuming that factory-length pushrods will suffice.

High-quality aftermarket performance roller lifters feature stronger roller bearings and are available with larger-diameter rollers that help to increase duration. High-performance lifter rollers are designed to accommodate higher valve spring pressures and higher engine speeds while maintaining durability. The example shown here is a roller lifter from Morel, a firm that also supplies roller lifters to several performance aftermarket cam and valvetrain manufacturers.

Depending on the height of the boss, a V-style tie-bar link may be necessary to provide clearance.

Roller lifters that feature a tie-bar link are available with either a straight link or a V-shaped link. The V-shaped link is available to provide added clearance between the link and the block’s bosses in the lifter valley.

Roller lifters that are connected by a tie-bar link are able to cycle vertically in their bores, and the links are better than the OEM plastic lifter guides at preventing lifter rotation.

Written by Mike Mavrigian and republished with permission of CarTech Inc

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