Valve Adjustment Procedure

The Easy and Correct Way

Our customers often ask us to explain the correct procedure for adjusting the valve lash on their engines. We’re often told that the service manuals, instructions included with their camshafts, or the advice from others is often confusing or varies substantially between each source. Such variations of the techniques or procedures to perform this engine maintenance task should not exist. The information and step-by-step procedure provided below should make it easy for just about everyone reading this article to understand—from the professional technician, engine builder or racer, to the home mechanic / do-it-yourselfer (DIY) attempting this task for the very first time.

Please read this entire article to understand correct valve adjustment procedures for most V-type engines. We can also help later with any specific questions or issues not covered here.

Introduction to Adjusting Solid and Hydraulic Lifters

The simplest way to adjust a hydraulic or solid lifter camshaft, whether it is a flat tappet or roller cam, is described below. However, the FIRST step is to forget all the old information we have collected from other individuals, magazines, shop manuals, and most instructions sheets have taught us in the past.

Interpreting the information below incorrectly, or trying to merge the steps presented with old knowledge is a recipe for destruction, and could create more trouble and confusion than necessary. Next, consider those things that can affect the engine’s valve lash, because it is important to understand the basic definitions, terminology, and functions before we can officially begin.

Before adjusting the valves on the engine, other possible issues and considerations must be addressed. Simply putting a wrench on something and attempting to follow the cam card, shop manual, or advice of some friend or relative is not enough. The basics of how the valvetrain works is where we begin—and only after answering a few important questions.

What type of camshaft is in the engine? (Hydraulic, Solid, Hydraulic Roller, Solid Roller, Mushroom Tappet)

Does the engine use steel (cast iron) or aluminum cylinder heads?
Are the correct valvetrain components installed on the application? (Proper valve stem and pushrod length, correct lifters, correct rocker arms and retention)
Are ALL of the valvetrain components in proper working condition?
Are the valve springs the correct size and tension for the camshaft and intended use (operating RPM)?
What type of driving (or racing) will this engine experience? (Daily driver, street/strip, racing, type of racing)
Are the proper tools available, and do we possess the basic knowledge required to perform this task?

The last one above is quite important. If after reading through this information and you find that you are still a bit confused, please ask for help or have someone else do it. In the very least you can have someone who is more knowledgeable walk you through the process we describe here to make sure you understand the procedure. If you are wondering what can go wrong, here is a short list that describes a few troubling results.

Poor running engine and low performance
Failed smog test (if this is an emission-controlled, street driven vehicle)
Burnt exhaust valve(s)
Broken valvetrain components (springs, pushrods, lifters, camshaft)
Limited or reduced lifespan of valvetrain components
Excessive valve guide and valve seat wear
Blown up engine
Lose an important Race!
Empty, or put a substantial dent in your bank account

The above list, though quite simple to understand, should scare us! It takes only a few thousandths of an inch (0.001″) of adjustment error to cause any one or more of the problems listed above.

IMPORTANT WARNING:

For those using OEM-style Ford, Chrysler, GM LS-Series, and other engines that utilize “Non-Adjustable” valvetrain … WE MUST verify that our machinist performed their tasks correctly when setting the valve stem heights, and then WE MUST also verify proper plunger depth when using Hydraulic Lifters. If switching to solid lifters it is mandatory that we convert to an adjustable valvetrain. It is always beneficial to convert to adjustable valvetrain, and mandatory for ALL racing applications as well as any application that demands accurate control of the valve lash setting). Not doing so is asking for serious problems!

Please Note

This article was written somewhat backwards, and there is a very good reason for doing so. It is important that the reader of this article is exposed to the procedure and then describe how it works and why it works. Experience has shown that although the reader was asked to forget what was learned in the past regarding this procedure, such grand requests rarely occur. For some, the whole experience of adjusting an engine’s valvetrain is confusing enough. Trying to erase embedded knowledge is often something that sounds good but is out of reach, and not a rational request.

To compensate for this, while understanding how people think and retain information, the reader will be exposed to the procedure first. This will hopefully generate a bit of thought and understanding that is clarified later in the article.

Please read through ENTIRE article before attempting to adjust the valve lash on the engine!

Understanding "Opposites"

It's all about the firing order

To begin, it is important to understand what is meant by “opposites” in the engine’s firing order. All engines have a specific firing order, or the sequence in which the compressed air and fuel mixture for each cylinder is ignited by the ignition system. The design of the engine determines the firing order and is directly related to the engine crankshaft and camshaft. Both help determine the firing order—when the piston is at the top of the cylinder (TDC), or when each valve is closed or opened, and therefore, when the ignition system ignites the spark plug.

What does “Opposite” mean?

adjective
– situated, placed, or lying face to face with something else or each other, or in corresponding positions with relation to an intervening line, space, or thing:
– being the other of two related or corresponding things’

For our explanation we are looking for those cylinders that are opposite in the engine’s firing order. This is not opposite sides of the block, or odd versus even numbers. It is ONLY related to the engine firing order.

Examine this graphic, showing a common GM V8 engine with the 1-8-4-3-6-5-7-2 firing order. The front of the engine is to the right, and the ignition distributor sits at the rear of the engine behind the #7 and #8 cylinders.

The graphic shows that the odd-numbered cylinders rest on the left (common driver side) of the engine) top of the graphic), and the even-numbered cylinders rest on the right side (common passenger side) of the engine.

On the distributor cap, we can also see that the plug wires (lines connecting the cylinders to locations on the distributor cap) are not in numeric sequence (1-2-3-4-5-6-7-8). There is an arrow just off of center on the distributor cap that designates rotor rotation of clockwise. Beginning with the #1 location on the distributor cap (facing toward the front of the engine in this graphic), and following the rotation arrow, the firing order is clearly provided.

1-8-4-3-6-5-7-2

The firing order can now be cut in half, showing the OPPOSITES of the firing order. Take the first four numbers in the firing sequence and place them against the second four numbers in the sequence. We now have (1-8-4-3) and (6-5-7-2).

To understand more clearly, review the next graphic, where the numbers are positioned vertically. The first four numbers in the firing sequence are provided in the left column, and the second four numbers are positioned in the far right column. Using this firing order, the #1 cylinder is opposite the #6 cylinder, and vice- versa (#6 is opposite #1). #8 is opposite #5, #4 is opposite #7, and #3 is opposite #2.

Again, the firing order is required, and this ONLY works on V-type engines. For other engines, here are some common firing orders and their opposites. PLEASE VERIFY the engine’s firing order. Do not rely on the list below.

Engine	Firing Order	Opposites
AMC (most) V8	1-8-4-3-6-5-7-2	Same as example above
Buick V8 (most)	1-8-4-3-6-5-7-2	Same as example above
Chrysler Big Block & Hemi V8	1-8-4-3-6-5-7-2	Same as example above
Chrysler Small Block V8	1-8-4-3-6-5-7-2	Same as example above
Oldsmobile (1967-later) V8	1-8-4-3-6-5-7-2	Same as example above
Pontiac (1955-1981) V8	1-8-4-3-6-5-7-2	Same as example above
Ford 5.0L HO, 351W, 351C, 351M, 400 V8	1-3-7-2-6-5-4-8	1 & 6; 3 & 5; 7 & 4; 2 & 8
Ford (most other) V8	1-5-4-2-6-3-7-8	1 & 6; 3 & 5; 7 & 4; 2 & 8

Engine OFF Valve Adjustment Procedure

The Quick and Accurate Way

First, review the description below showing Small and Big Block Chevy, and other engines using the 1-8-4-3-6-5-7-2 firing order. is it easy to understand?A more detailed explanation follows below the chart. For other engines, use the firing order that matches the engine to create a similar chart.

Intake Valve Adjustment: ENGINE OFF!

- - with #1 cylinder Intake Valve at full valve lift …. Adjust #6 Intake Valve
  - with #8 cylinder Intake Valve at full valve lift …. Adjust #5 Intake Valve
  - with #4 cylinder Intake Valve at full valve lift …. Adjust #7 Intake Valve
  - with #3 cylinder Intake Valve at full valve lift …. Adjust #2 Intake Valve
  - with #6 cylinder Intake Valve at full valve lift …. Adjust #1 Intake Valve
  - with #5 cylinder Intake Valve at full valve lift …. Adjust #8 Intake Valve
  - with #7 cylinder Intake Valve at full valve lift …. Adjust #4 Intake Valve
  - with #2 cylinder Intake Valve at full valve lift …. Adjust #3 Intake Valve

Exhaust Valve Adjustment: ENGINE OFF!

It is obvious that this is the same procedure and sequence as the intake valves listed above. This time, ONLY the exhaust valves are being adjusted.

- - with #1 cylinder Exhaust Valve at full valve lift …. Adjust #6 Exhaust Valve
  - with #8 cylinder Exhaust Valve at full valve lift …. Adjust #5 Exhaust Valve
  - with #4 cylinder Exhaust Valve at full valve lift …. Adjust #7 Exhaust Valve
  - with #3 cylinder Exhaust Valve at full valve lift …. Adjust #2 Exhaust Valve
  - with #6 cylinder Exhaust Valve at full valve lift …. Adjust #1 Exhaust Valve
  - with #5 cylinder Exhaust Valve at full valve lift …. Adjust #8 Exhaust Valve
  - with #7 cylinder Exhaust Valve at full valve lift …. Adjust #4 Exhaust Valve
  - with #2 cylinder Exhaust Valve at full valve lift …. Adjust #3 Exhaust Valve

In the instructions above, adjustments are being made on the “opposite” valves in the firing order, specified by the engine rotation cycle. The example shows an engine with the firing order of 1-8-4-3-6-5-7-2. It is these opposites that position the opposing valve at the correct location for adjustment. That proper location is when the lifter resides on the back side (base circle, or heel) of the cam lobe (see previous image), meaning that the valve is in the fully closed position.

Please, DO NOT try to adjust both intake and exhaust valves at the same time. It is NOT accurate, and gets back to the original request of forgetting (or ignoring) what was previously known about valve adjustment procedures. Each valve is adjusted independently. That means specifically, that sixteen (16) individual adjustments will occur on a typical V8 engine.

Explanation of Terms

Providing definitions and explanations to the words and terms used throughout this article is probably necessary at this point. :

Full Lift – The valve is OPEN and the lifter is positioned on the nose (highest point) of the cam lobe.
TDC – Top Dead Center, or where the piston is at the top of the cylinder and both (all) valves for that cylinder are closed.
Lash – The clearance (cooling time) between the tip of the valve stem and the rocker arm.
Zero Lash – No clearance, where the rocker arm is snug to the lifter. On a hydraulic lifer, the plunger is in the uppermost neutral position (not compressed)
Camshaft Lobe Base Circle – Includes the ‘heel’ or bottom of the cam lobe. When the lifter is on the base circle of the cam lobe, the valve it controls is closed.
Camshaft Lobe Toe or Nose – The highest point of the cam lobe opposite the base circle, and where the valve is at its highest point (greatest opening, or full lift).
Camshaft Lobe Ramp – (also known as ‘lift’ or ‘rise’ on the valve opening side of the lobe, and ‘flank’ on the closing side.

A note on valve lash Only on solid lifter camshafts does a gap actually exist between the rocker tip and valve stem. On hydraulic lifters, there is no gap, and it is the oil within the lifter that provides the cooling time (lash), even though constant contact remains between the rocker arm and valve stem. This is one reason why hydraulic camshaft designs are quieter during normal engine operation than solid lifter designs.

Importance of Lifter Position

If the position of the lifter on the camshaft lobe is anywhere other than on the heel (reference the adjacent graphic) where there is NO ramp contact when making adjustments, the lash setting will be incorrect. Proper position of the lifter on the cam lobe is required for each valve before attempting to perform adjustment. The chart and procedure above ensures that the lifter is on the backside of the cam lobe for each valve.

In the past, service manuals and our auto shop teachers instructed us to position each piston an at TDC for that cylinder (piston at Top Dead Center), and then adjust both valves for that cylinder. However, we often find that this is not the correct procedure to obtain a proper valve lash setting, especially on modern engines or those with aggressive camshaft profiles. The image shows the required position of the cam lobe relationship to the lifter to ensure the foundation for performing the correct valve lash adjustment.

Lifter Position on Camshaft Lobe Ensuring that the lifter is positioned on the heel of the cam lobe will guarantee that the valve being adjusted is fully closed. Any other position and adjustment will NOT be accurate.

What About the Actual Adjustment Procedure?

Hydraulic Lifter Camshafts

It is time to describe the actual wrench turning. How many of us read or were taught that with a hydraulic lifter camshaft, we must adjust it down to where there is slight pushrod resistance (zero lash) and then turn it down 3/4 to a full turn? I was originally taught the wrong way too, both by instructors and by following inaccurate procedures in various shop and service manuals. When we followed these methods, our adjustment likely opened the valves slightly. This prevented the valves from closing all the way, causing a poor-running engine and other issues. Our valves were not set correctly using these methods!

The typical hydraulic lifter requires an adjustment that is roughly half the available travel of the plunger. If an average hydraulic lifter plunger has a range of 0.060″ (sixty thousands of an inch) of travel from fully compressed to its static height where the pushrod seat is up against the retaining ring, half of that distance is +/- 0.030″ (thirty thousands of an inch). This means that the valve must be adjusted to fall between the depth that the plunger in the lifter drops. If adjusted too tight (the plunger fully compressed) the valve will remain slightly open. The valve must fully close when in the closed position. A partially open, or improperly adjusted valve both removes the important cooling time (lash) that removes heat from the valve stem, and creates a poor-running engine.

If the adjustment is too loose, the valvetrain will be loud, and damage may occur to the valve tip (top of the valve stem), rocker arm, push rod, pushrod seat, the lifter, and camshaft lobes.

How do we achieve a 0.030″ or centered plunger depth? On new lifters or newly assembled engines, using a dial indicator and manually compressing the plunger to measure the distance of travel is the easiest method. On new lifters, outside of the engine, carefully using a press (even a drill press) with dial indicator attached works well. On an complete engine, especially one already in the vehicle this is somewhat harder to do. Again, use a dial indicator with the tip positioned on the valve spring retainer usually works well.

I have two procedures to adjust hydraulic lifters. One is what I call the “clean” method, where the engine is turned off, and the other is the “messy” method, with the engine running and squirting oil everywhere. I prefer a “clean” adjustment, and only use the messy method as a last resort. When the “messy” method is the only option is described below.

For the messy method, rocker arm clip-on oil deflectors, modified old valve covers, or other techniques are necessary steps to keep the oil in the engine and from spraying everywhere. Preventing oil from splashing all over the engine compartment and off the ground is an intense chore that takes consideration and planning!

Engine "OFF" Hydraulic Lifter Adjustment Tips:

If the engine is complete and installed in the vehicle, warm up the engine by running it until it gets to operating temperature (15-minutes or so). “Cold” adjustments should only be used on new engines as a preliminary adjustment on the engine stand. Once a new engine has been started and the initial break-in procedures complete, re-adjusting the valves “hot” is recommended.

Have all necessary tools ready and then quickly remove the valve cover(s) after the engine has achieved operating temperature.
Begin the adjustment procedure by using the chart provided above in this article, or one to match your engine firing order and document the opposites.
With the #1 Intake valve at FULL LIFT — This means turning the engine by hand until the intake valve on the #1 cylinder is fully open (watch the rocker arm push down on the top of the valve stem, compressing the valve spring until it stops moving downward) — and adjust the intake valve on “opposite in firing order” cylinder. Always remember, adjustment occurs on the opposite valve based on the engine’s firing order.
Go to the opposite cylinder. This technical article uses the common firing order for small and big block Chevy engines as the example, so this would be the #6 cylinder.
Loosen the rocker nut (if using roller rockers there is typically a Jam Nut that requires loosening with an Allen wrench) on the #6 intake valve.
Take two fingers and spin the pushrod back and forth between them to feel for resistance.
Carefully snug the adjustment nut and STOP when resistance is felt on the pushrod as it applies pressure to the seat of the rocker arm and lifter, this is considered “zero lash.”
Turn the wrench 1/8 to 1/4 turn (see below) for performance, racing, or high RPM applications. Turn the wrench 1/4 to 1/2 turn for stock or mild street applications. For applications that regularly operate at consistent high RPM, use the slightly lighter setting of (1/8 turn).
If this valvetrain uses poly-locks, remember to reset (snug) the Allen screw
The adjustment for this valve is now complete!
Turn the engine by hand SLOWLY to the next cylinder / valve in the firing order, again finding full lift of the next valve.
Repeat the above steps, starting at #3 through #10, but use the next cylinder in the sequence. In our Chevy V8 example this is the intake valve for the #8 cylinder
Continue through all the intake valves and then start the procedure over for the exhaust valves.

What Describes 1/4 Turn? (see image below)

This is another area that has been taught wrong in auto shop classes and very expensive service manuals since the 1950’s. Imagine the hands on a clock. We have the obvious 12:00, 3:00, 6:00, and 9:00 o’clock positions as well as the numbers in-between those points. Start with your wrench at the 12:00 position and turn it clockwise to the 6:00 position you have just made 1/2 turn. Going from 12:00 to the 3:00 position would be 1/4 turn. Many manuals say to adjust the valves three quarters to one full turn … THIS IS INCORRECT!!!!

PRECAUTION When working on older high mileage engines or those that use poor quality lifters you may experience a condition where the lifters bleed off pressure (drain the oil out of the lifter body), causing inaccurate valve adjustment. Oil must remain in the hydraulic lifter in order to achieve an accurate valve lash setting. If repeated attempts to adjust the valves using the "cold adjustment" procedure fails, lifters bleeding off may be the cause. two options exist to solve this issue. ONE: replace the lifters or TWO: adjust the valves using the "HOT" running method described below.

TIP: One way to tell if a lifter is bleeding off or not retaining oil consists of watching the rocker arm while applying the 1/8 to 1/2 turn of the wrench. If the rocker pushes the valve stem down instead of the pushrod, the vale is opening instead of adjusting the lifter!

Engine RUNNING Hydraulic Lifter Adjustment

Who like oily spills and messes? Adjusting the valves on an engine can be one of the most miserable and messy maintenance procedures when we do not properly plan ahead.

Some helpful hints:

Adjust only one side of the engine at a time.
Use oil restrictors (deflectors) on the rocker arms, or better yet a butchered up old valve cover that has an access cut into the top of it to facilitate adjustment access AND oil deflectors
Stay calm … getting burnt a bit is common. Messes can occur no matter how careful. If not adjusting the valves properly the first time through, it doesn’t get easier or become less of a frustration.
Using a mechanic’s stethoscope can make this task substantially easier, especially if the engine is loud or we have hearing issues.

Adjusting hydraulic lifters with the engine running is not one of my favorite activities. With the above considerations addressed we are ready to get started:

Start the engine and allow it to warm up.
Turn off the engine
Remove one valve cover and install the deflector clips, custom valve cover, or whatever apparatus available to keep oil splash to a minimum.
Start the engine back up.
Begin to loosen one of the rocker arm adjusting nuts. The valvetrain will begin to gently “clatter” like an old sewing machine.
Slowly tighten the rocker nut down, just until the louder volume of “clatter” reduces.
Turn the wrench an additional 1/8 – 1/2 turn to set the plunger depth to the proper lifter preload. (see information above)
Continue (repeat) this procedure on each of the remaining the valves.
Turn off the engine
Remove the oil splash prevention apparatus and re-install the valve cover.
Repeat these steps on the other engine bank (if a V-type engine).

If the engine runs rough or poorly, or is making excessive valvetrain noise, repeating the procedure on at least the troublesome valve(s) will be required—something went wrong. As stated above, having access to a mechanic’s stethoscope can help. Position the tip of the stethoscope upon the top of each rocker stud to compare the noise levels. Listen to the sounds. A loose adjustment should be obvious, which helps finding and correcting “zero” lash easier.

Important Warning If a mess occurs, PLEASE use environmentally conscious methods to clean up any and all oil spills. Be certain to check the oil level in the engine to ensure proper capacity. It may surprise some at how quickly, and how much oil can spill while performing engine-running valve adjustments in unable to contain all of the oil in the engine!

Solid Lifter Adjustment

The steps for solid lifter adjustment are similar to hydraulic lifter adjustments. However, instead of turning a wrench 1/8 to 1/2 turn to position the internals of a hydraulic lifter we use a feeler gauge to set and verify a specific, measured lash setting.

First, warm the engine to operating temperature (about 15-minutes) and then quickly remove both valve covers. Follow the adjustment firing order sequence chart above. With the #1 Intake valve at FULL LIFT. This means turning the engine by hand until the intake valve on the #1 cylinder is fully open (watch the rocker arm push down on the top of the valve stem, compressing the valve spring until it stops moving downward). Adjusting the intake valve on “opposite in firing order” cylinder (see the above chart) is now possible. Remember, the opposite is engine firing order dependent. This article uses the small and big block Chevy engines as the example, so this would be the #6 cylinder. Loosen the rocker slightly (if using roller rockers there is typically a Jam Nut that requires loosing an Allen set screw (use the properly sized Allen wrench).

Based upon the cam card (cam specifications provided by the camshaft manufacturer) the valve lash setting is typically provided on the card. Most measurements are provided in thousandths of an inch for both the exhaust and intake valves. For some camshafts these clearances will be the same (intake and exhaust), and others may show a value higher (more cooling lash) for the hotter exhaust valve.

For example, a cam card recommends a valve lash setting of 0.022″. Use a 0.022″ feeler gauge and place it between the top of the valve stem and the rocker arm tip. Snug down the rocker “just” until you begin to feel resistance. Move the feeler gauge continuously, gently sliding the feeler gauge back and forth on stock style slotted rocker arms, or side-to-side if using roller tip rocker arms. The valve lash setting should not be tight — the feeling should feel similar to sliding a table knife through a stick of cold butter. Not too hard, not too soft. It is beneficial to use “positive-lock” style rocker arm retention fasteners instead of the basic pinched rocker nuts or Nylox. If using rocker nuts the job is done, go to the next valve. If using positive-locks, hold the body of the lock in place with a box end or open end wrench (there are special tools available to simplify this procedure for those who want to spend the $$$ on them) and then carefully tighten the Allen set screw in the center of the posi-lock.

NOTE: In most cases the Allen set screw will make a slight “click” when it is tight.

Compensating for a Cold Engine When Adjusting the Valve Lash

When installing a new camshaft, the engine will obviously be cold as it sits there on an engine stand. The problem is that the provided lash specifications are for an engine that has been running long enough to be at normal operating temperatures. What can we do in this situation? There is a standard correction factor that can be used to get us close to the required settings. We must now consider the material alloys of the various engine parts and components, because the thermal expansion of these components affect the valve lash in different ways. Therefore the correction factor used for our lash setting will depend upon whether the cylinder heads and block are made out of cast iron or aluminum.

Take the “hot” setting provided to in the cam manufacturer’s catalog or from the cam card that came with the camshaft. Use the figures below to alter the original lash specifications to get a “cold” lash setting.

Using iron block and iron heads, add .002″
Using iron block and aluminum heads, subtract .006″
Using both aluminum block and heads, subtract .012″

Warning This correction adjustment is only an approximation. It is only meant to get the valve lash "close" for the initial new engine start up. After properly warming up the engine to normal operating temperatures, go back and readjust all the valves to the specified "hot" valve lash settings.

Using Valve Lash to "Tune" Engine Performance

This is a little extra tip often unknown to many engine builders and tuners. Most people do not realize that we can make subtle performance improvements by slightly reducing or increasing the recommended lash settings. NOTE: This is for SOLID LIFTER camshafts ONLY (tappet or roller)!

The intake and exhaust valves cannot move until all the running clearance (valve lash) has been taken up. Therefore, the amount of valve lash used affects an engine’s performance. For example, by reducing the amount of (hot) valve lash, the valve will open slightly sooner, provide slightly more lift (valve opening), and will close slightly later. This makes the camshaft seem bigger to the engine, due to this slight increase of duration and lift. Increasing the amount of (hot) lash the opposite occurs. The valve will open later, provide slightly lift less, and close slightly sooner. Now the engine sees a smaller cam with slightly less actual duration and lift. BE CAREFUL – It is suggested to begin with only 0.001 – 0.003″ of change to the base valve lash specification. Crazy experimentation can destroy an engine!

Use this tuning method to experiment, as a way to find something the engine may respond to. Keep the setting that works the best. Just remember, the more valve lash, the louder the valvetrain will be—and damage may occur if not careful. If the clearance is excessive, damage can occur to other valvetrain components. Therefore, it is not recommend to increase the amount of lash by more than +0.004″ from the recommended lash specification. Similarly, reducing the lash by more than -0.008″ is not recommended.

Common gains or performance differences include:

- Reducing the lash will increase top end (upper RPM power) horsepower
- Increasing the lash can improve low end torque and acceleration

Closing Remarks & Tips

As mentioned above, the power band can change slightly on an engine using a solid lifter camshaft by varying valve lash settings. A looser lash setting increases the low-end power of the engine where a tighter lash increases top-end power. Careful consideration is necessary for these tweaks because the valve lash is the “Cooling Time” that the valve needs on each reciprocal cycle. If the engine has too little, or no lash, damage to the valves is possible.
Using roller rocker arms dramatically increases valve guide life, increases horsepower and is also better at maintaining valve lash settings. Use them whenever you can! Shaft style rockers are best (less deflection). Stainless steel rockers provide less “over the valve weight”, which is GOOD. Aluminum, though less expensive will deflect more and increase the actual weight over the valve stem, but are still better than stamped steel or OE-style rocker arms. The added weight may not seem critical, but this is considered reciprocal weight, which slows down all the components related to it.
Additionally, a valve lash setting that is too loose can damage the valve stem and increase the possibility of premature failure of the roller rocker tips. If using OEM style, stamped steel rocker arms, fracturing of the rocker arm or galling at the fulcrum is possible.
Engine materials, engine operating RPM, and valvetrain deflection contribute to varying valve lash settings. The higher the RPM, the cheaper the parts in use, and the performance and reliability differences between types of materials contribute to more frequent valve lash adjustments. (By the way, while the valve covers are off, make the effort to test the valve spring pressures. There are tools available for installed testing of spring pressures).
There is FREE horsepower when using a Roller Camshaft. If within the budget, use a roller cam! Plus, when using a roller cam, camshafts changes can occur without the need to change lifters or endure those annoying, yet extremely important, camshaft and lifter break-in procedures. This process is mandatory with Hydraulic or Solid “tappet” camshafts.

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