Hyd 'roller' Pre-Load Question...?
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Hyd 'roller' Pre-Load Question...?

  1. #1
    Super Moderator HammerDown's Avatar
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    Question Hyd 'roller' Pre-Load Question...?

    Question...should there be a difference in hyd roller pre load on Iron vs Aluminum heads?
    My Lunati cam paper work reads 1/2 turn after zero lash. With my iron 049's I'm a heavy 1/2 turn. But no mention of iron vs aluminum heads.
    Also... a friends builder suggest 1/16'th of pre load on his Comp hyd rollers. Maybe he feels this is to guard against lifter pump-up >his engine revs to 6K.
    I always thought... 1/4 turn was the minimum. He says his engine is very noisy clickty-clack
    Feedback ?
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    LP-25.com Infomaniac's Avatar
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    FWIW I put 1/2 turn on all of them regardless.

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    steelcomp was here
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    1/16 turn is only a little over .003". If this is done cold, alum heads will definitely grow more than that, and lash will be .002-.003" open. Not good, and why they're noisy. I set hyd. lash at 1/4 turn, plus whatever it takes to tighten the poly, usully another 1/8 turn or so. It comes out to be almost 1/2 turn.
    1/4 - 1/2 turn is fine. I wouldn't go more than 1/2.
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    E-7 Sheepdog (ret) SmokinLowriderSS's Avatar
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    This is why you are supposed to set the valves HOT, not on a cold engine.
    Only set cold to get it close enough to get it running.

    Get the engine warmed up and then take 15 min. and do one head.
    The minor loss in temp will not be enough to matter.

    Re-warm it up, and do the other.

    Unless of course you "modify" a set of sheet metal valve covers to open them up and catch the oil spray and set them running warm like you are really supposed to.
    "As democracy is perfected, the office of president represents, more and more closely, the inner soul of the people. On some great and glorious day the plain folks of the land will reach their heart's desire at last and the White House will be adorned by a downright moron."
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    steelcomp was here
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    That's really not necessary with hyd's. In fact, one of the reasons to go hyd is so you don't have to adjust them hot. Most alum headed engines won't see much more than .005"-.006" change in lash so anything between 1/4 and 1/2 turn will be more than anough to compensate.
    Quote Originally Posted by SmokinLowriderSS View Post
    This is why you are supposed to set the valves HOT, not on a cold engine.
    Only set cold to get it close enough to get it running.

    Get the engine warmed up and then take 15 min. and do one head.
    The minor loss in temp will not be enough to matter.

    Re-warm it up, and do the other.

    Unless of course you "modify" a set of sheet metal valve covers to open them up and catch the oil spray and set them running warm like you are really supposed to.
    If God is your co-pilot, change seats!
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    Some guy obnoxious001's Avatar
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    Quote Originally Posted by HammerDown View Post
    Question...should there be a difference in hyd roller pre load on Iron vs Aluminum heads?
    My Lunati cam paper work reads 1/2 turn after zero lash. With my iron 049's I'm a heavy 1/2 turn. But no mention of iron vs aluminum heads.
    Also... a friends builder suggest 1/16'th of pre load on his Comp hyd rollers. Maybe he feels this is to guard against lifter pump-up >his engine revs to 6K.
    I always thought... 1/4 turn was the minimum. He says his engine is very noisy clickty-clack
    Feedback ?
    Interesting question, sure to get a variety of results. Crane used to recomend .020-.060" preload, or 1/2- 1 full turn. Others will use different specs, but I have always set at about 5/8-3/4 of a turn, dating back to when I assembled a large number of marine engines for a big name shop back in the early 90s

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    Super Moderator HammerDown's Avatar
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    Quote Originally Posted by obnoxious001 View Post
    Interesting question, sure to get a variety of results. Crane used to recomend .020-.060" preload, or 1/2- 1 full turn. Others will use different specs, but I have always set at about 5/8-3/4 of a turn, dating back to when I assembled a large number of marine engines for a big name shop back in the early 90s
    Thanks for the feedback fellas...I'm sure this thread will be viewed by the boats owner. If he wants to chime in that's up to him.
    I personally felt 1/16th turn is on the edge and could cause problems when things expanded with heat.

    If spring pressure and other factors are set right >at what RPM should one really worry about a decent hyd roller(morel, comp etc) pumping up?

    Smoken, I know some ole school guys that still set their hyd tappets when the engine's runing...back'em off till you hear the tap-tap then carefully take'em down 1/2 turn.

    Thanks again for the feedback
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    Each engine will vary. With the Morels in Iron headed boat engines a 1/2 to 3/4" seems to be the range. With engines running aluminum heads and Morels 3/4" to a full turn seems to be the range.

    On street engines I have had a few guys call about the Morels being noisey. These are usually show cars that maybe get 1000 to 2000 miles a year. A full turn on these cars has always fixed the noise problem.
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    E-7 Sheepdog (ret) SmokinLowriderSS's Avatar
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    Quote Originally Posted by HammerDown View Post
    Thanks for the feedback fellas...I'm sure this thread will be viewed by the boats owner. If he wants to chime in that's up to him.
    I personally felt 1/16th turn is on the edge and could cause problems when things expanded with heat.

    If spring pressure and other factors are set right >at what RPM should one really worry about a decent hyd roller(morel, comp etc) pumping up?

    Smoken, I know some ole school guys that still set their hyd tappets when the engine's runing...back'em off till you hear the tap-tap then carefully take'em down 1/2 turn.

    Thanks again for the feedback
    My hyd flat is a full Iskendarian kit, cam, lifters and recomended springs. The lifters are their "Superlifters", which, supposedly, according to Isky will not pump up untill after 7-grand (the box says so).
    I'll never have it happen, not staying under 6.

    When the cam is dropping away from the lifter fast enough to apreciably redeuce the spring pressure driving the lifter down, oil pressure pumps the lifter more full than normal.
    Stiffer valve springs help delay the onset of pump-up, as does lighter valves (reducing the inertia of the valve wanting to stay in place open)
    Pump up is not just RPM driven, but also oil pressure driven.
    Same engine setup, pump-up will happen much earlier to the engine running 80PSI oil pressure than to the engine running 60PSI oil pressure.

    Lifter pump up is a "balancing act" held in check by valves that are not over-heavy, oil pressure not excessively high, and springs not excessively weak, all at once.

    No real way to say, with any accuracy what a given combination's "threshold" is, unless you deliberately attempt to find it.
    "As democracy is perfected, the office of president represents, more and more closely, the inner soul of the people. On some great and glorious day the plain folks of the land will reach their heart's desire at last and the White House will be adorned by a downright moron."
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    E-7 Sheepdog (ret) SmokinLowriderSS's Avatar
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    I always advise preload to the lifter-maker's specs, not what anyone else says either.
    My lifters are to be set 1/4 turn down from 0-lash, so they are.

    An old memory from the 80's says SBC's stock were 3/4 turn.
    "As democracy is perfected, the office of president represents, more and more closely, the inner soul of the people. On some great and glorious day the plain folks of the land will reach their heart's desire at last and the White House will be adorned by a downright moron."
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    Years ago I measured a bbc 1 wrench flat = .010. On alum. I would go 1.5 flats from 0 jm2cent

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    steelcomp was here
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    Quote Originally Posted by pisston in the wind View Post
    Years ago I measured a bbc 1 wrench flat = .010. On alum. I would go 1.5 flats from 0 jm2cent
    The thread pitch on a BB Chev rocker stud is 20 TPI (threads per inch) which is .050" per turn. There are six sides to a hex nut, so .050/6 = .0083" per flat.

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    Quote Originally Posted by Infomaniac View Post
    FWIW I put 1/2 turn on all of them regardless.
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