Hydraulic Lifter/Tappet Explaned!

Discussion in 'Ranchero Tech Reference & Articles' started by 5.0 Chero, Jun 8, 2008.

  1. burninbush

    burninbush In Maximum Overdrive

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    Theoretically this could work. You could set to zero lash, collapse the lifter, measure the gap, devide the preload by the rocker ratio, and reduce the gap by that amount. >ribald

    ++++++++++++

    Ahhh ... I think we're communicating. I wouldn't have said it quite that way. This is what all Ford manuals advise to check if pushrod length is in range, e.g., a proxy for preload within range.

    Don't understand what you meant by your last sentence -- looking for power. Are you working the assumption that lifters will collapse at high rpms, or ??? Or did you switch to solid lifters?

    Here's the Ford manual; last para in the middle column makes it clear.
     

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  2. CJ Guy

    CJ Guy In Maximum Overdrive

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    BB, you...Never mind...:D Geometry is the push rod length ref diagram a to set it up correctly, that has to be correct or premature wear and failure of springs/valve tips/guides will occur.
    As for the dial indicator method, I trust it to run my engines more so than 1/2 or 3/4 turn or where ever, I like to know that where I set things is correct...:rolleyes:
     
  3. burninbush

    burninbush In Maximum Overdrive

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    As for the dial indicator method, I trust it to run my engines more so than 1/2 or 3/4 turn or where ever, I like to know that where I set things is correct...:rolleyes: >CJ

    +++++++++++++++

    Yeah, I hear that. But do you work from a collapsed lifter or from the first-touch of the pushrod [fully expanded lifter]? Collapsed seems to me to be much less ambiguous.

    What's wrong with the Ford manual method? [Again, assuming you have already worked out the geometry.]
     
  4. ribald1

    ribald1 Banned PLATINUM MEMBER

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    The best way to test geometry is to install soft springs, use a magic marker on the valve stem, and turn the engine over. The wear spot should be a thin line exactly in the middle of the valve stem.
     
  5. ribald1

    ribald1 Banned PLATINUM MEMBER

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    The geometry has to include the preload. There are two ways to do it, either 3-d modeling, or the method I indicated above. Using that method, you have to use shorter pushrods to allow for the preload.
     
  6. ribald1

    ribald1 Banned PLATINUM MEMBER

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    Addendum.
    As the geometry changes with oil pressure and RPM, one gets into a tail chasing exersize with hydraulic lifters.
    As valve opening times, and lift change with oil pressure and RPM, one needs to be very conservative about timing and compression with hydraulic lifters.
    As the lifter is likely to fail under stress, weak valve springs must be used, limiting one to inefficent cams, and low top RPM's.

    To put it bluntly, if you want power, go solid.
     

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