taintedsoul

Hey all,doing a h/c/i on my ls1 and have a question about the preload.I have looked through tons of threads and seems like everyone talks about the ls7 lifters.I am using the original lifters and the heads have been milled(dont know how much) went from 71cc to 68cc and a texas speed cam,head gasket is also .003 thinner.I used a pushrode check and at zero lash i came up with 7.330,so i tried 7.375 and it gave me 3/4 of a turn and at 7.400 it gave me 1 1/8 turn.I am not trusting my outcome since it is so close to stock length.what would you guys suggest?

jasons69chevelle

Not sure what LS7 lifters recommended preload is, maybe .1 also it’s best to use calipers the pushrods checkers can be off in actual measurements. If you’re on base circle and you have 0 lash at 7.330 you just need to add in your lifters recommendation on preload. Check all 16, then measure what you ordered and what actual measurements are of the new pushrods.
get lifters on base circle of cam.
Rockers are torqued down to spec, then use the checker, opening it till there is 0 lash, then add your preload to the measurements.
if your reusing the stock lifters and trays you might want to consider new oem trays
while your in there replacing lifter wouldn’t be a bad idea.

taintedsoul

Yea thats what im trying to figure out,i have just the plain ole ls1 gm lifters and not sure what the preload should be,everything i see talks about the ls7 lifter preload.I did replace the trays tho.i didnt change the lifters as i will probably only have this motor for another year then switch

Jake Wade

Honestly, you will be good with either length.

grinder11

iTrader: (1)

With 7.300" or 7.400"?? That's a LOT of variance! I suspect 7.375" would probably be mighty close. But 7.300"?? May not have ANY preload, or damn little. I've never heard of anyone running 7.300" long pushrods in any LS engine. Some extreme examples, maybe. But a .010"-.020" mill, I'd be concerned some lifters would have no, or very little, preload. My .02....

Jake Wade

He said 7.375 and 7.400 from what I gathered.
.025 difference

taintedsoul

Yes zero lash was 7.330,with the checker set at 7.375 it gave me 3/4 turn on rocker bolt,7.400 gave me 1 1/8 on bolt.

grinder11

iTrader: (1)

As I said, I think 7.375 is probably where you need to be. This makes sense since they came with 7.400 length pushrods, and you have milled heads.

grinder11

iTrader: (1)

Yeah, I misread it a bit, but I did say 7.375", which I think would be about right considering the cut heads. LS7 OEM lifters have .200" travel, so there's quite a bit of room to play with...

taintedsoul

cool thanks for the help jake and grinder