Engine Repair
Car Engine Repair Tips
Valve Adjustment
Introduction to Adjusting Solid and Hydraulic Lifters:

    The simplest way to adjust a hydraulic or solid lifter cam whether it is a tappet or roller cam is described below. But FIRST, what you need to forget about is all that information that many individuals (and books) taught you in the past. In many cases, if interpreted wrong you could be in for more trouble than before you tried to adjust the valves yourself. Think about things that can affect your valve lash, you will need this bit of common sense before you get into this, because there are other considerations besides just putting a wrench on something and attempting to follow the cam card, or shop manual.

What type of cam are you running? (Hydraulic, Solid, Hydraulic Roller, Solid Roller, Mushroom Tappet)
Are you running aluminum heads?
Are ALL of your valvetrain parts in proper working condition?
Are your valve springs the correct ones for the camshaft and operating RPM?
What type of driving (or racing) are you going to be using the engine for?
Do you have the tools and basic knowledge required to adjust your own valves?
    The last one is quite important. If after you read through this and are still a bit confused, give up and have someone else do it, or have them at least walk you through it to make sure you understand the procedure. Now, if you are wondering what can go wrong there is a quite a few bad things that can occur:

Poor running engine and low performance
Failed smog testing (if this is a smog-legal street driven vehicle)
Burnt exhaust valve(s)
Broken valvetrain components (springs, pushrods, lifters, camshaft)
Limited lifespan of valvetrain components
Excessive valve guide and seat wear
Blown up engine
Lose an important Race!
Empty Bank Account
    The above list, though quite simple to understand, should scare you. It takes only a few thousandths of an inch of adjustment error to cause those problems. Now lets' get to the actual process. I am going to simplify this a bit, so if your valvetrain is somewhat different you will need to verify the correct procedure for your application.


IMPORTANT NOTE: 
   Those of you with Ford, and other engines with "Non-Adjustable" valvetrain ... YOU MUST verify that your machinist did his job correctly when setting the valve stem heights, and then YOU must also verify proper pintle depth when using Hydraulic lifters. If you switch to solid lifters it is nearly mandatory that you convert to adjustable valvetrain (I'd say this is mandatory in all RACING applications as well as any application where you want to actually have control of your valve lash setting). 

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Valve Adjustment The Quick Way:


   Ok, now to the good stuff! First, view this little chart for Small and Big Block Chevy Engines that I made and see if you can understand it ... for other engines, use your firing order that matches your engine to do the same. You set up this procedure based upon "opposite" cylinders of your firing order. (see below)

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!

If you have noticed, this is the same procedure as the intake valves listed above, just that you are now adjusting the exhaust valves the same way.

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 

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Need an explanation?

   Well, what you have here is "opposite" valves on the engine cycle. The small and big block Chevy engines use a firing order of 1-8-4-3-6-5-7-2. What you do is separate the order into the two sides of the firing order. These are "exact" opposites that put the opposing valve at the correct location for adjustment, meaning the back side (base circle, or heal) of the cam lobe (see image at left). This procedure works on most V8 and V6 engines. (base circle, or heal) of the cam lobe (see image at left). This procedure works on most V8 and V6 engines. (base circle, or heal) of the cam lobe (see image at left). This procedure works on most V8 and V6 engines. (base circle, or heal) of the cam lobe (see image at left). This procedure works on most V8 and V6 engines.

1  -  6

8  -  5

4  -  7

3  -  2


    If the lifter is anywhere other than on the heal of the cam where there is NO ramp contact you will have incorrect lash. The chart above makes sure you are on the backside of the cam lobe. When the cylinder is at TDC, this is not often the correct location to get the proper lash setting.

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What about the actual adjustment procedure you ask?

Hydraulic Cams:

    Ok, let's get to the actual wrench turning ... how many of you read or were taught that with a hydraulic lifter cam you adjust it down to where there is pushrod resistance (zero lash) and then turn it down 1/2 to 3/4 turn?  Well, if you did this, you more than likely have the valves not closing all the way!

    The hydraulic lifter requires roughly a .030" pintle depth setting. This means that you adjust valves by the depth that the pintle in the lifter drops. Too tight and the valves do not close, too loose and they rattle and do not open properly and damage the lifter. How do you get .030"? Well, on new engines I will actually use a dial indicator and measure the depth of travel. On an engine in the car this is a bit different, and harder to do..

    Now, I have two ways that I use to adjust hydraulic lifters. One uses the "clean" method with the engine off and the other is the messy way with the engine running.


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Engine "OFF" Hydraulic Lifter Adjustment:


    Warm the engine by running it until it gets to operating temperature (15-minutes or so). Have all your tools ready and then quickly remove the valve cover(s) and start the adjustment procedure by using the chart above. With the #1 Intake valve at FULL LIFT (this means that you spin the engine until the Intake valve on the #1 cylinder is fully open ... you can tell this by the rocker arm pushing the down until it goes no further) you can now adjust the "opposite in firing order" cylinder (see the above chart). In the small and big block Chevy engines this is the #6 cylinder. Loosen the rocker (if using roller rockers there is a Jam Nut that you must loosen with an Allen Wrench). Now, with two fingers spinning the pushrod between them to feel for resistance you easily snug the adjustment nut. When you feel resistance STOP, now you will adjust the nut down "Only" 1/8-1/2 turn. If you operate your engine a consistent high RPM, use the lighter setting (1/8 turn).

What is 1/4 turn? (see image at right)
   Well, imagine the hands on a clock. You have the obvious 12:00, 3:00, 6:00, and 9:00 settings as well as the numbers in-between those. If you 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.  What is 1/4 Turn?

click image to enlarge 

    Now, you will do this for all the intake valves and then do the exhaust valves the same way.

PRECAUTION: If you have an older high mileage engine that the lifters bleed off pressure (drain the oil out of). You can improperly adjust your valves. You need oil in the lifters to be able to get an accurate setting. If you repeatedly adjust the valves this way and they are still not correct, you probably have lifters bleeding off during adjustment. You have two options: Replace the Lifters  -= or =- adjust the valves the "HOT" method as below.


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Engine RUNNING Hydraulic Lifter Adjustment:


    Ok, so you really like messes? This has to be one of the most miserable maintenance procedures if you do not properly plan ahead.

Some helpful hints:

Adjust only one side of the engine at a time.

Use oil restrictors on the rocker arms, or better yet a butchered up valve cover that has an access cut into the top of it to facilitate adjustment access.


Stay calm ... you WILL get burnt, you WILL make a mess and you WILL not look forward to doing this again, especially if you screw up the first time.

Using a mechanic's stethoscope can substantially make this procedure easier

    Adjusting hydraulic lifters with the engine running is not one of my favorite activities (as you can tell). With the above considerations taken care of, start the engine and loosen one of the rockers. You should hear it just start to "clatter". Slowing tighten it down until the "clatter" just stops and then turn it 1/4 - 1/2 turn additional to set the pintle depth. Continue on all the valves. If you hear excessive noises or the vehicle runs crappy you will be doing the procedure again. As stated above, if you have access to a mechanic's stethoscope, you can set the end at the top of the rocker stud to listen to the noise a loose adjustment makes, which will make finding "zero" lash easier.

NOTE: If you make a mess, PLEASE check your oil level once you are done.


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Solid Lifter Adjustment:

    First warm the engine to operating temperature (about 15-minutes) and then quickly remove the valve covers. Follow the chart above. With the #1 Intake valve at FULL LIFT (this means that you spin the engine until the Intake valve on the #1 cylinder is fully open ... you can tell this by the rocker arm pushing the down until it goes no further) you can now adjust the "opposite in firing order" cylinder. In the small and big block Chevy engines this is the #6 cylinder. Loosen the rocker (if using roller rockers there is a Jam Nut that you must loosen with an Allen Wrench).

    Now, based upon your cam card (cam specs) you should know what the valve lash setting should be. Let's say that your valve lash setting is .022". Get out the .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 fell resistance. The valve lash setting should not be tight ... the feeling should be about the same as putting a knife through a stick of cold butter. Not too hard, not too soft. Now, hopefully you are using "positive-lock" rocker arm retention instead of just pinched rocker nuts or Nylox. If using rocker nuts your 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 for this available) and then tighten the Allen screw. 

NOTE: In most cases the Allen screw will make a slight "click" when it is tight. Now, go adjust the remaining valves.


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Closing Remarks:

You can change the power band a bit when using a solid lifter motor 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. Also, be careful because the valve lash is the "Cooling Time" that the valve needs on each cycle. If you have no lash you take a chance of burning the valves.

Using roller rockers dramatically increases valve guide life, increases horsepower and also maintains better valve lash settings. Use them when you can!

Too loose a valve lash setting can damage valve stem tips as well as roller rocker tips, and can crack OEM stamped steel rocker arms.

Engine materials, engine operating RPM and valvetrain deflection contribute to varying valve lash settings. The higher the RPM, the cheaper the parts you use and the different types of materials contribute to sooner need for valve lash adjustments. (By the way, while you are in there ... test your valve spring pressures).

There is FREE horsepower when using Roller Cams ... if you can afford it, do it. Plus, when using roller cams, you can change cams without the need to change lifters which is mandatory with Hydraulic or Solid "tappet" cams.
 

 
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