Question on lifter preload and lifter plunger.
this measurement is incorrect, and your desired preload is incorrect with an aftermarket cam
first off...aftermarket cams want to see .020~.060 preload...and yes, it does make a difference, the extra ramp rate will want less preload to make it quieter, and it will make slightly more power with less preload, and have more valve control.
secondly...the math for preload needs to account for rocker ratio as well
so ...Thread pitch of 1.25 = .0492126
but that assumes 1:1 rocker....
with a 1.7:1 rocker (stock LS1), it becomes 0.0492126 + (0.0492126/1.7) = .078161 per one turn of rocker bolts......
if you dont believe me, Use a Dial indicator, and you will see one turn is .078
first off...aftermarket cams want to see .020~.060 preload...and yes, it does make a difference, the extra ramp rate will want less preload to make it quieter, and it will make slightly more power with less preload, and have more valve control.
secondly...the math for preload needs to account for rocker ratio as well
so ...Thread pitch of 1.25 = .0492126
but that assumes 1:1 rocker....
with a 1.7:1 rocker (stock LS1), it becomes 0.0492126 + (0.0492126/1.7) = .078161 per one turn of rocker bolts......
if you dont believe me, Use a Dial indicator, and you will see one turn is .078
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There is a ton of misinformation in this thread, and it's on both ends of the spectrum. If you aren't going to buy a $20 checker, please just follow Shane's instructions that were posted above. No less than 1 turn of the bolt should be considered acceptable with gm lifters. If possible I like 1 1/4 to 1 1/2, it will be quiet and stable. A little more is acceptable and is generally not a problem.
Frank
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If you are at 1 5/8 turns, your preload is almost .125"-.130" you are going to want no more than 1 full turn. If you had 3/4 of a turn that would put you at .058" preload. That is all with just tightening the bolt to snug (not torqued to 22ft lbs).
Last edited by poltergeist 02; Sep 24, 2013 at 10:44 PM.
On The Tree
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1 turn has already been established to be .047". That makes 1 5/8 turn .0766" Not sure where you come up with .125"-.130""? That would be over 2 5/8" turn.
You are not placing the rocker arm ratio in to the equation. Let me put it this way. I have LS7 lifters that I set up with .098" preload. I checked with a pr length checker and a dial indicator to be certain that my measurement was correct. With .098 preload and stock 1.7 rockers I get about 1.25 turns.
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From: Turnin' Wrenches Infractions: 005
The rocker is being drawn down vertically, ratio has NOTHING to do with crap. Ratio is when the rocker spins on its axis, a rocker floating in mid air and being lowered by a bolt travels vertical. Big difference over-thinkers. Shane's method is proven and works, period. Do what you want with you engine I could care less.
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Verdad Gallardo The rocker is being drawn down vertically, ratio has NOTHING to do with crap. Ratio is when the rocker spins on its axis, a rocker floating in mid air and being lowered by a bolt travels vertical. Big difference over-thinkers. Shane's method is proven and works, period. Do what you want with you engine I could care less.
On The Tree
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You are not placing the rocker arm ratio in to the equation. Let me put it this way. I have LS7 lifters that I set up with .098" preload. I checked with a pr length checker and a dial indicator to be certain that my measurement was correct. With .098 preload and stock 1.7 rockers I get about 1.25 turns.
I don't see how rocker ratio is a factor. You're not using the rocker to muliply the preload.
On The Tree
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No, I'm just wondering why you're the only one who has ever brought up rocker ratio in lifter preload. I'm trying to understand your theory but I don't see how the ratio affects it. So, you're claiming the rocker muliplies the ratio when setting preload?
Your taking your measurement is as if the bolt is directly above the lifter. As you tighten the bolt one end of the rocker arm is planted on the valve, then the other end of the rocker is pushing on the pushrod/lifter. When the bolt is being tightened the rocker arm pivots acting as a lever creating more preload than the said .047. For that pitch thread on the rocker bolt, one full rotation actually equals .049 of bolt movement. and at the tip of the rocker, it will see .078 of movement.
Yes, and I know this for a fact as I have measured several ways to confirm of this.
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From: Turnin' Wrenches Infractions: 005
You said your piece, now move along. That's why I hate people like you who try to cram your opinion down people's throat. If you were right I STILL wouldn't listen because you are annoying and that makes people not like you. I said what I had to say, OP can do what he likes. That's what I meant from I could care less. Jeez its like talking to a woman. 
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This is getting good. Frank, no one is denying that the method mentions earier says one turn equal .047. That was written by some one on the internet too.
This debat is only going to end with a video of some one going to zero lash on base circle, and putting a dial indicator on and going one turn.
Im mentallt torn on whether the ratio argument makes sense.
This debat is only going to end with a video of some one going to zero lash on base circle, and putting a dial indicator on and going one turn.
Im mentallt torn on whether the ratio argument makes sense.
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01ssreda4, I think you need to move on. This is a good thread that hasn't been ruined by personal attacks yet. I for one encourage guys like poltergiest. What if they are right? Then we have way more preload then we thought.
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Oh and thanks for saying again the op can do whatever he wants. Really?? I didn't know i could. Sound engeneer and poltergeist have said they have straight up measured this **** that means a lot.
Could they be wrong? Sure. I vote we need a video
Could they be wrong? Sure. I vote we need a video