lifter preload setting>>

Small Block Mopar Engine

  1. challenger57

    challenger57 cuda57

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    Well I have my new cam in from previous thread, and I am switching rockers to adjustable rockers. Usually I just use the old stamped rockers or solid lifters. How much adjustment for hyd. lifters and adjustable rockers. 1/2 -3/4 - 1 full turn? Thanks
     
  2. RustyRatRod

    RustyRatRod Lemmie see your b00bs. FABO Gold Member

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    I usually only go half a turn. Other opinions will vary I am sure.
     
  3. TrailBeast

    TrailBeast AKA Mopars4us on Youtube

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    I always preferred to do the final adjustment while the engine is idling so just in case 1/2 turn didn't quite do it and it was noisy.
    Same with stamped adjustables like Chev has.


    Watch, now we will have 45 posts about it by tomorrow. :D
     
  4. mopowers

    mopowers Well-Known Member

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    Who's lifters are you using? I'd ask them. They'll be able to give you the preload spec. Keep in mind the spec is in thousandths of an inch. You'll need to know the thread pitch of your adjusters to figure out how much rotation in the adjuster gives you the appropriate preload. From what I've seen, .5 turn will usually work fine.
     
  5. mguner

    mguner How many is too many?

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    Hot Rod did a test from just touching to just off the bottom and there wasn't but about 4 HP and 4 FT LBs of torque difference between the two settings at the crank on a dyno. I prefer the just in setting incase a lifter sticks. You have around 0.150 to play with.
     
  6. DusTed74

    DusTed74 Well-Known Member

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    I know that Crane recommends .060" of preload. And as said in post #4 you really should find out what the thread pitch is in the rocker arm.
    So lets say it has a 16 thread per inch thread. Then one full turn would give you .062" of travel.
    Then sometimes you just have to do it the way TrailBeast says, while it's running. Messy but effective.

    Ted
     
  7. mderoy340

    mderoy340 Well-Known Member

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    Set them to what the cam instructions list. You can use a spark plug wire gap tool, the one with the small 90* bend on the end to check how many turns your adjuster needs to setup the spec.
     
  8. moper

    moper FABO Gold Member FABO Gold Member

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    Preload depends on the lifter manufacturer, your block, and your cam. They spec is normally between .005-.090". The number of turns will depend on the rockers but normally 1/4 turn is .010. Personally unless it's a high-rpm type lifter I'll usually aim for .060".
     
  9. AJ/FormS

    AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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    .020 to start. Back to .020 as soon as one or two start ticking. I like 7200 rpm with no lifter pump-up. And I'm willing to reset the preload once in a very great while.
    I can tell you one thing; 1/4 turn during break-in,was not enough, on my Hughes 5003s!
     
  10. nm9stheham

    nm9stheham Well-Known Member

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    We just put .040" in our 340 crane lifters and AL heads; that was 4/5ths of a turn on a 24 tpi adjuster. Keep in mind, with AL heads, the rocker shaft is going to move up more with thermal expansion, so more preload is needed to compensate the larger AL movement.
     
  11. moper

    moper FABO Gold Member FABO Gold Member

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    It is for the anti-pump-up or variable duration lifters. Most of them want less than .010".
    It is all subjective - so talk to your manufacturer.
     
  12. challenger57

    challenger57 cuda57

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    Spoke with comp. cam about their lifter preload and they suggested 1/2 - 1 full turn depending on the tpi of the adjuster should give .050 to .100. I currently gave them 1 full turn which moved them about .040. going to wait until it is running and let them get a good pump up and then recheck.
     
  13. RustyRatRod

    RustyRatRod Lemmie see your b00bs. FABO Gold Member

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    That's a fact. As a matter of fact, some anti pump up lifters spec a little valve lash, like .002".
     
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