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Properly Adjusting Hydraulic Lifter Pre-Load

Discussion in 'T-Bucket Engine and Driveline Articles' started by Mike, May 24, 2008.

  1. Mike

    Mike
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    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.
     
  2. MDANIELSON55

    MDANIELSON55
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    your firing order is for sure chevy the valves should be 2 diff settings. like 24 and say 32 all according to cam i slightly loosten all. i need to see rocker move which ever one your working on if one is up check lash find center of lash set up rocker to the center and set the other rocker to specks. then one u set run to center up and set the other then that piston is done move to aother simple and works if you watch intake you set exhaust and vice versa.lash is checked by wheel or degree on flywheel or measure the lifter by mm or in.
     
  3. Mike

    Mike
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    Lash on a hydraulic lifter? ;) :welcome:
     
  4. gudgyz

    gudgyz
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    This is something often over looked and can limit how well your engine with a hydraulic cam performs. It doesnt take long and if you like to rev your engine you may notice the difference. If i wasn't racing my T I would sometimes race my tow car, which would spin happily to 6800-7000rpm with a hydraulic cam.

    I like Mikes method, which is pretty much what i used to do. Treat it like a solid cam, and adjust them one at a time. I always went the slow way, turn the engine over until one valve was wide open then adjust the opposite rocker on that cylinder. I would back the rocker off until you could just turn the push rod between your finger and thumb, which means theres no preload on the lifter, then nip it down by 1/4 turn.

    Alternatively if you don't mind a potential mess with oil everywhere....

    If you've got an old tin rocker cover i found the easiest way was to cut a strip out of the top of it, in line with where the rocker nuts are, dont cut out too much or you will get oil everywhere. Fit the cover to one side of the motor, start it and while the engines idling back of the nuts until the rocker starts to "tick" then tighten it up 1/4 turn.

    I'm not saying this is gospel BUT both these worked well for me over the years. (I did it the first way, after the mess with a cut cover)
     
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