Adjusting hydraulic lifters
by: Alittle1, Cobalt327, Crosley
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Overview
The following is information and instructions on how to successfully adjust the preload on adjustable hydraulic lifter valve trains. For non adjustable valve trains, refer to Fast and Easy Way to Check Hydraulic Lifter Preload when using Non-Adjustable Rocker Arms from Crane.
A word on the correct length pushrod
To obtain the correct valve train geometry, the correct length pushrod needs to be determined and installed before setting the lifter preload. Below are some things to check that could have changed the correct pushrod length:
- Camshaft base circle diameter
- Pushrod length due to wear or replacement
- Milling heads/block
- Different thickness head gaskets
- Valve seat height changes from seat replacement or from valve seat grinding/cutting done during valve jobs
- Grinding the tip of the valve stem when doing a valve job or different length valves
- Lifter height due to different manufacturer
- Change in rocker arm type or design, or ratio
How much preload should I use?
The recommendation given below to use 1/2 to 1 turn past zero lash is based on what has been shown to work well when using stock or performance hydraulic lifters. However, the amount of preload may be different, depending on the type and brand of hydraulic lifters being used. For example, there are Rhodes lifters that are set using a feeler gauge- something that's traditionally reserved for solid lifters. Always refer to the manufacturer's instructions first before proceeding. If the manufacturer's instructions differ from those given here, follow the manufacturer's recommendations.
Should I "pump up" my lifters with oil before installing them?
Generally speaking, no. The lifters can be dipped into a container of oil but unless the manufacturer's instructions tell you otherwise, there's no need to pump the lifters up before installing them.
There are some exceptions to this. For instance Rhodes lifters DO recommend their "original" lifters be pumped up prior to installing and adjusting them to 3/4 of a turn, or so the lifter cup is about 1/16" below the retainer. The Rhodes "V-Max" lifters are adjusted so the plunger is from 0.010" to 0.030" from being fully compressed- quite different than 'normal' hydraulic lifters are adjusted.
Can I replace a damaged lifter with a new lifter?
Before replacing a stuck or noisy lifter (which should only be done as a LAST resort), disassemble the lifter that is in question. You will see a cup, spring and check ball retainer (left) snapped onto the bottom center of the "piston" of the lifter. Often all that has happened is the cup assembly isn't fully seated into the recess on the bottom of the piston, or a speck of dirt has lodged between the check ball and seat.
Remove the cup using a pick and see that the (tiny) spring and ball are there and that the ball isn't scored and that the seat on the piston that the ball seals, doesn't have any ridge or imperfections that would prevent the ball from seating properly.
Shown above, left, is a disassembled GM hydraulic roller lifter. Most current flat tappet lifters have the same internal construction as this roller lifter, although there are different styles. But as long as the styles are the same, the piston from one can usually be fitted into another body. The arrow shows the location of the cup, spring and check ball assembly mentioned above.
A better choice if the lifter's piston is found to be unrepairable, would be to replace the piston from another identical lifter, and reuse the lifter body that has broken in to the lobe that it started life running on. The lifter foot and the cam lobe quickly wear in together to become a unit- using a new lifter risks wiping out the cam lobe. This is also why it is not recommended to replace a used set of lifters with a new set on a used camshaft.
The lifter body ID and the piston OD are a very close tolerance fit- the closest tolerances in the entire engine. Because of this, there's a chance that one piston won't work the exact same as the original. As long as the piston doesn't fit too tightly, this won't be a problem in the vast majority of cases, but should be mentioned just the same. The clearance between the piston and body is what regulated the bleed down rate. But having a slightly different bleed down rate is much preferred over putting a new lifter onto a used cam lobe in this writers opinion.
Chevy OEM hydraulic roller cam and lifters
Warning: According to Crane's Director of Valvetrain Research and Development, Mark Campbell, valve lifts of more than 0.530 inch at the valve with a 1.5:1 rocker can allow the lifter to fall deep enough into the lifter bore (because of the lobe's small base circle) that the steel retainer can lose its grip on the lifter body. This allows the lifter to spin in the bore and destroy the camshaft.
Crane sells a long travel lifter, p/n 10535-16a that will work for reduced base circle/high lift cams.
Before beginning you will need to know:
The firing order
- Firing orders of various engines
- The Chevy V8 is 1-8-4-3-6-5-7-2
The direction the distributor rotates
- The small block Chevy V8 is CW
The order of the valves as they are located in the cylinder head
- The small block Chevy V8 is E - I - I - E - E - I - I - E
Other engines can be found at the BoxWrench site.
The adjustment procedure
The following adjustment procedure is based on instructions originally from Crane Cams. It is recognized by many as being the "go-to" method of valve adjustment. This method also works on any OHV engine using hydraulic lifters that has an adjustable valve train. Some possible differences between various engines are the:
- Firing order
- Order of the valves in the cylinder head
- Number of turns to set the preload
- Distance of the plunger below the retainer
Adjusting hydraulic lifters for proper preload
EO/IC Method (Exhaust Opening/Intake Closing)
- In order to adjust the preload, the lifter must be properly located on the base circle or "Heel" of the lobe.
At this position the valve is closed and there is no lift taking place. You will need to watch the movement of the valves to determine when the lifter is properly positioned for adjusting.
1. Remove the valve covers, and pick a cylinder that you are going to set the preload on.
2. Hand rotate the engine in its normal direction of rotation and watch the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder's intake rocker arm. (Why? Because when the exhaust valve is just beginning to open, the intake lifter will be on the base circle of the lobe- the correct position for adjusting the intake.)
3. Back off the intake rocker arm adjuster and remove any tension from the pushrod. Wait a minute or two for that hydraulic lifter' push rod seat to return to the "up" position. The spring inside the lifter will move the pushrod seat up against the retaining lock if you give it time to do so. (If you are installing brand new lifters they will be in the "up" position when they come in the box.)
4. Now spin the intake pushrod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the pushrod, you are at zero lash. (If you are uncertain that you are feeling when all the lash has been removed (the "zero lash" point), jiggling the push rod up and down can give a better sense of when all the clearance has been removed.) Turn the adjusting nut down one half to one full turn from that point. Lock the adjuster into position if using polyloks. The intake is now adjusted properly.
NOTE: If using stock-type lock nuts, no further action is required. Do be sure to use new lock nuts if using that type; old lock nuts can back off and the preload will be lost. Do not use lock nuts on aftermarket studs or the threads will be damaged. Follow the manufacturer's instructions.
5. Continue to hand turn the engine, watching that same intake. It will go to full open and then begin to close.When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. (Again, when we see the intake almost closed, we are sure that exhaust lifter is on the base circle of the lobe.) Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.
6. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.
Something that you also might find useful, is go to How To Make A Timing Tape. This temporary timing tape will allow you to check and set the total timing even if you don't have a timing light that reads advance or a degreed damper. You can also use it to permanently mark the damper for full advance, etc. as you see fit.
If there's any doubt as to whether or not the timing mark on the damper and the timing tab is accurate, refer to Determining top dead center.
Adjusting lifters using a video presentation
Sometimes a video presentation helps to fill in the voids in describing a written direction of a project. Valve lash adjustment video
Resources
- Crankshaft Coalition Wiki articles
