TTG

That would put me at about .062.

Jenson

iTrader: (32)

Yes they fit. Your math is confusing me. .005" shorter push rod nets you .012" less preload?

Jenson

iTrader: (32)

Would ya just look at it;
https://ls1tech.com/forums/generatio...l#post17388244

.200 worth of travel.

Jenson

iTrader: (32)

I measured mine last night as well, also in the .200" travel range

vettenuts

iTrader: (4)

Huh? 0..005" shorter pushrod should net 0.005" shorter preload on the lifter.

TTG

Yeah, I screwed up somewhere. I have exceeded my capacity for number crunching for an entire year. Jarheads dont usially think this much, lol!
9.125 turns x .050 + 6.8" base length = 7.25625, -7.325 = .06875. So basically it would be .069 preload.

01ssreda4

iTrader: (96)

I'm running about 60/75 preload now but have seen as high as 120 with no issue.

cam

iTrader: (9)

I like .0080 after running as low as 50, and as high as 120. 80 seems best, been very high in RPM, no tick. 120 winked pistons, 50 worked great but ticked like crazy.

kinglt-1

iTrader: (26)

I would try to get around .080 preload with LS7 lifters.

TTG

The next step up from 7.325 is 7.35. That would add .025 to .069, which would put it at .094. I think thats too high. I would rather have it a little low than a little high i think.

Jenson

iTrader: (32)

At least your doing better at math today!

kinglt-1

iTrader: (26)

That is not too high at all. LS7 lifters like a lot of preload coming around .200 travel...it's a spongy lifter. Most shoot for .070-.090. 7.325 will put you on the light end of acceptable. Try it and see how it ends up.

TTG

ha ha! Yes, I am fresh off the coffee pot!

TTG

I have been told it has .160, then .180, now .200! Which is the real number??

TTG

Just got off the phone with comp. The ls7 lifters have between .160 and .166 cup travel. 7.300 would put me at .044 preload. 7.325 - .069, and 7.35 - .094. With a target of half or a little under half, he recomends definately going with the .069 preload. Lighter could cause valve train separation, and higher could cause lifter failure or lower rpm. So its settled! Thanks all for the help, and catching my fuzzy math! I will update the thread when i get it going and let everyone know how it works out.

kinglt-1

iTrader: (26)

Comp is the last place I would call for information.One thing you are not accounting for is heat expansion which will cause about a .012 loss in preload. So you your .069 will be .057 when up to temp. This topic has been discussed a thousand times over the years here. I just googled "LS7 lifter plunger travel" and came up with pages of results. Here is one thread with info.
https://ls1tech.com/forums/generatio...066-091-a.html

another good read here.

https://gwatneyperformance.com/lifte...ont-hurt-will/

BlwnLs1GTO

iTrader: (12)

.080 is ALWAYS my target preload on LS7 lifters. I've never had an engine tick or sound like a sewing machine at this preload. Trust me, that sound is annoying.

Also,
What about your different sized banks? I may have read your original post wrong, you're not running two different head gaskets are you? Don't
You should be just fine running a 11/32" PR with a preload near or at .080" IMO. Again, IMO. Also, it's always a good idea to measure each and all 16 valves for the proper preload.
I've found many rebuilt engines with severe differences in between valves. Especially if the heads/valves have been worked on. It only takes one value with minimal preload to make noise.

Good Luck with your build!

Floorman279

iTrader: (11)

i have seen the expansion discussed......i was thinking it still wouldn't change anything because it all is getting hot and expanding. but then i started thinking, an aluminum block will be a little warmer than the heads so the block may expand a little more than the heads. thus tightening up preload

G Atsma

A block expanding would LOOSEN preload, not tighten it. The block/heads expand more than the pushrods, thereby increasing distance between cam and rocker arm.

kinglt-1

iTrader: (26)

If the aluminum block and heads expand, that means growth, which is similar to making the push rod shorter since it didn't change with heat... thus reducing preload. You increase push rod length to add preload not the other way around.