Mike
Well-Known Member
How do you adjust the pre-load on your hydraulic lifters?
Through the years, I've seen and heard a dozen different methods, nearly all of which do little more than create an oil spill on the garage floor and leave the valve adjustments nowhere near being close.
So let's walk through the correct process of adjusting hydraulic lifter pre-load.
(In a perfect world, you would have the intake manifold off the engine, so you could actually measure how much pre-load a quarter-turn of the adjuster would give you. Most camshaft manufacturers will recommend a pre-load figure of between .020" to .060". In most (and please note, I did say 'most' and not 'all') applications, a half-turn of the adjuster will amount to around .020" to .024" of pre-load. If you can verify this on your engine as you are assembling it for the first time, so much the better.)
For this article, we're going to assume that you are adjusting pre-load on an engine that has been running.
1. Remove the valve covers from the engine.
2. Focusing on the #1 exhaust valve, slowly rotate the engine (preferably by hand) until you see the exhaust valve just start to open. That will ensure the #1 intake lifter is on the heel or base circle of the camshaft.
3. Back the intake rocker adjuster off, removing any pre-load that was already set and wait for a couple minutes. This will allow the plunger in the lifter to return to a neutral position.
4. Now you can roll the intake pushrod back and forth, between your thumb and forefinger, as you slowly tighten the adjuster. When you feel the pushrod offering resistance to the rolling motion, stop tightening the adjuster. You are now at zero lash.
5. You now want to tighten the adjuster, to provide something in the .020" to .030" range of lifter pre-load. (If you verified your adjuster on a new assembly, then turn the adjuster that same amount.) So turn the adjuster another one-half to three-quarters of a turn. This will provide the necessary pre-load. If the adjuster has a locking device, lock it down.
6. Now turn the engine slowly, watching for the intake valve to go to full lift. As the intake valve begins to close from full lift, you are now ready to adjust the exhaust pre-load. Now follow Steps 3, 4 and 5 for the exhaust rocker.
7. You have now adjusted the valves on the #1 cylinder.
At this point, you can move to the next cylinder on that same side of the engine and follow the same procedure, adjusting the intake rocker when the exhaust valve just starts to open and adjusting the exhaust rocker when the intake valve just starts to close from full lift.
If you are working on an engine that has a fully-degreed harmonic balancer and has a 90° firing order, there is a method that will minimize all the engine turning. For the purposes of this explanation, we will assume the engine has a firing order of 1-8-4-3-6-5-7-2.
Turn the engine until you see the #1 exhaust valve just starting to open. Adjust the #1 intake rocker as explained in Steps 3, 4 and 5, above.
Once the #1 intake rocker has been adjusted, turn the engine 90° and you will then be able to set the #8 intake rocker. Follow this procedure as you move through the firing order.
Once you have adjusted the #2 intake rocker, you can move back to the #1 cylinder. Turn the engine until you see the #1 intake valve just starting to close from full lift. Adjust the #1 exhaust rocker as explained in Steps 3, 4 and 5 above. Then turn the engine 90° and adjust the #8 exhaust rocker. Once again, just follow the same procedure until you have adjusted the #2 exhaust rocker and you are then finished.
Through the years, I've seen and heard a dozen different methods, nearly all of which do little more than create an oil spill on the garage floor and leave the valve adjustments nowhere near being close.
So let's walk through the correct process of adjusting hydraulic lifter pre-load.
(In a perfect world, you would have the intake manifold off the engine, so you could actually measure how much pre-load a quarter-turn of the adjuster would give you. Most camshaft manufacturers will recommend a pre-load figure of between .020" to .060". In most (and please note, I did say 'most' and not 'all') applications, a half-turn of the adjuster will amount to around .020" to .024" of pre-load. If you can verify this on your engine as you are assembling it for the first time, so much the better.)
For this article, we're going to assume that you are adjusting pre-load on an engine that has been running.
1. Remove the valve covers from the engine.
2. Focusing on the #1 exhaust valve, slowly rotate the engine (preferably by hand) until you see the exhaust valve just start to open. That will ensure the #1 intake lifter is on the heel or base circle of the camshaft.
3. Back the intake rocker adjuster off, removing any pre-load that was already set and wait for a couple minutes. This will allow the plunger in the lifter to return to a neutral position.
4. Now you can roll the intake pushrod back and forth, between your thumb and forefinger, as you slowly tighten the adjuster. When you feel the pushrod offering resistance to the rolling motion, stop tightening the adjuster. You are now at zero lash.
5. You now want to tighten the adjuster, to provide something in the .020" to .030" range of lifter pre-load. (If you verified your adjuster on a new assembly, then turn the adjuster that same amount.) So turn the adjuster another one-half to three-quarters of a turn. This will provide the necessary pre-load. If the adjuster has a locking device, lock it down.
6. Now turn the engine slowly, watching for the intake valve to go to full lift. As the intake valve begins to close from full lift, you are now ready to adjust the exhaust pre-load. Now follow Steps 3, 4 and 5 for the exhaust rocker.
7. You have now adjusted the valves on the #1 cylinder.
At this point, you can move to the next cylinder on that same side of the engine and follow the same procedure, adjusting the intake rocker when the exhaust valve just starts to open and adjusting the exhaust rocker when the intake valve just starts to close from full lift.
If you are working on an engine that has a fully-degreed harmonic balancer and has a 90° firing order, there is a method that will minimize all the engine turning. For the purposes of this explanation, we will assume the engine has a firing order of 1-8-4-3-6-5-7-2.
Turn the engine until you see the #1 exhaust valve just starting to open. Adjust the #1 intake rocker as explained in Steps 3, 4 and 5, above.
Once the #1 intake rocker has been adjusted, turn the engine 90° and you will then be able to set the #8 intake rocker. Follow this procedure as you move through the firing order.
Once you have adjusted the #2 intake rocker, you can move back to the #1 cylinder. Turn the engine until you see the #1 intake valve just starting to close from full lift. Adjust the #1 exhaust rocker as explained in Steps 3, 4 and 5 above. Then turn the engine 90° and adjust the #8 exhaust rocker. Once again, just follow the same procedure until you have adjusted the #2 exhaust rocker and you are then finished.
:welcome:
