Lifter preload delema
Thread Starter
Teching In
Joined: Jul 2018
Posts: 31
Likes: 0
Lifter preload delema So, I’m having a bit of a delema. I built a stroked ls6. Here are the quick specs.
Callie’s compstar forged stroker kit, h beam rods, Manley pistons with 6cc dish 3.905 dia.
deck plained, prc heads milled (~62cc), using .040 Cometic Head gaskets. When the machine shop did the head milling, they were supposed to leave the Pistons .080 down, but ended up with the odd bank .0040 up and the even bank .0085 up above deck. I ordered an .045 Cometic head gasket to equal them out at around .0040 up. With my gaskets I should wind up with an .036 quench height. I am running a comp cam with 614 int, 621 exh, duration at .050 is 227 and 235, with 113 lsa. Using ls7 lifters. With all that said, I am trying to figure out pushrod length. I measured with comp’s tool, but have come to a roadblock with lifter preload. I did tons of internet searches and ther seems to be 0 consensus. Looking to learn from your mistakes, lol! What should my preload be?
Callie’s compstar forged stroker kit, h beam rods, Manley pistons with 6cc dish 3.905 dia.
deck plained, prc heads milled (~62cc), using .040 Cometic Head gaskets. When the machine shop did the head milling, they were supposed to leave the Pistons .080 down, but ended up with the odd bank .0040 up and the even bank .0085 up above deck. I ordered an .045 Cometic head gasket to equal them out at around .0040 up. With my gaskets I should wind up with an .036 quench height. I am running a comp cam with 614 int, 621 exh, duration at .050 is 227 and 235, with 113 lsa. Using ls7 lifters. With all that said, I am trying to figure out pushrod length. I measured with comp’s tool, but have come to a roadblock with lifter preload. I did tons of internet searches and ther seems to be 0 consensus. Looking to learn from your mistakes, lol! What should my preload be?
Last edited by TTG; Jul 30, 2018 at 10:29 PM. Reason: Misspell
Not sure I follow, the pistons are out of the hole 0.040" on one bank and 0.085" on the other? Not sure how that happens through head milling. I am confused so hard to determine what needs to be done.
Last edited by vettenuts; Jul 31, 2018 at 07:17 AM.
TECH Addict
Joined: Oct 2016
Posts: 2,513
Likes: 480
From: PDX-OR-USA
If all that was machined was the heads,, that wouldn't have affected this..
Is the block line bored off center?
Or is it decked funny?
I wouldn't be able to do it,, I'd have to take the block to someone and have the crank/cam/deck heights figured out..
Is the block line bored off center?
Or is it decked funny?
I wouldn't be able to do it,, I'd have to take the block to someone and have the crank/cam/deck heights figured out..
Thread Starter
Teching In
Joined: Jul 2018
Posts: 31
Likes: 0
The odd bank was decked approximately .0045 more than the even bank by the machone shop. I assume by accident.
Last edited by TTG; Jul 30, 2018 at 11:31 AM. Reason: Misspell
Thread Starter
Teching In
Joined: Jul 2018
Posts: 31
Likes: 0
I dont get why the difference in numbers. I have seen people say .08 and up to .100, and others say .08 is too high and they get lifter noise. Others say .050 or less, but then people say that can cause inadequate valve lift. Most things are cut and dry. This is more of a preference thing then?
Trending Topics
Thread Starter
Teching In
Joined: Jul 2018
Posts: 31
Likes: 0
FYI, i got 9.25 turns on the measuring tool. So 9.125x .05= 0.45625 +6.8=7.25625. Plus whatever preload. I was leaning toward .050. So that would make it 7.30625, or 7.30. Is there a more definative way to decide a more exact target preload? Seems like im just hoping for the best here.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Wait wait wait, so thats a typo I hope. .085 out of the hole + a .04 head gasket = piston hit head. So .008" and not .08" I hope? I thought Ls7's worked better in the .07 to .08 (or even the .100 as stated above) preload range for a build of this nature. More preload on the lifter simply lessens the amount of oil in it, kinda like a short travel lifter.
ooo somehow i missed the decking issue....i used the measuring tool but measured end to end with a caliper not count turns.
from my research, a general rule of thumb with hyd roller lifters that i have read is no more preload than half the lifter total travel.
from my research, a general rule of thumb with hyd roller lifters that i have read is no more preload than half the lifter total travel.
Thread Starter
Teching In
Joined: Jul 2018
Posts: 31
Likes: 0
Wait wait wait, so thats a typo I hope. .085 out of the hole + a .04 head gasket = piston hit head. So .008" and not .08" I hope? I thought Ls7's worked better in the .07 to .08 (or even the .100 as stated above) preload range for a build of this nature. More preload on the lifter simply lessens the amount of oil in it, kinda like a short travel lifter.
I might lean a little more towards .08ish preload which will get you near .09 hot. Some say travel is .180 and some say .220. You just want to be near the middle, best bet would be to measure the travel yourself and go for the middle
As for the lifter preload question, I'm not sure but with what you're describing with the pistons being so far out of the hole and way higher on one side, I'd be far more concerned with that and not just moving past it.
I see a motor lasting about 5 seconds here..
Thread Starter
Teching In
Joined: Jul 2018
Posts: 31
Likes: 0
Same here. Doesn't make any sense at all to me.
As for the lifter preload question, I'm not sure but with what you're describing with the pistons being so far out of the hole and way higher on one side, I'd be far more concerned with that and not just moving past it.
I see a motor lasting about 5 seconds here..
As for the lifter preload question, I'm not sure but with what you're describing with the pistons being so far out of the hole and way higher on one side, I'd be far more concerned with that and not just moving past it.
I see a motor lasting about 5 seconds here..
Last edited by TTG; Jul 30, 2018 at 10:38 PM. Reason: Add info
OK, that makes a little more sense. The standard tolerance on a pushrod length is +/- 0.005" so the difference side to side may not matter much. If you have a set of calipers, you could measure the pushrods once you get them and any longer ones set aside for one bank just so you are not doubling up on tolerance stacks. I would also strongly consider larger OD pushrods, it is a good way to stiffen up the valve train and add stability. Don't know too much about the LS7 lifters, but many seem to run in the 0.070" preload area.
Thread Starter
Teching In
Joined: Jul 2018
Posts: 31
Likes: 0