99Bluz28

iTrader: (35)

I come up with 5/8 to 7/8 turn of preload with using the supplied YT rocker shims, torqued to 22ft.lbs.. Do I need to use a different amount of preload with the LS7 lifters, or am I good-to-go already?

Thanks!

outkast6991

iTrader: (34)

don't know if it helps but i was told to stay between .030 and .080 with ls7's

RARON455

iTrader: (35)

Yup, the recommended lifter preload value does not change due to changing rockers. I believe I read that the max preload on LS7 lifters is around .120 then bottom out.

99Bluz28

iTrader: (35)

Well the shims are 1mm/.03937" thick if I can find some .5mm/.019685, or slightly thicker shims that should put me in the .05 -.06 range.
Any body know a good/quick source of shims (5/16" hole with a 3/4" outer dia.) ?

vettenuts

iTrader: (4)

The YT shims are not used to set preload, they are used to set geomtery (wipe pattern). You need to verify the wipe pattern first, then determine the correct pushrod length. If you are following LS1howto.com, it is wrong with the methods used for installation. Here is how you set them up: Link

RARON455

iTrader: (35)

I just finished my install, I have the 6645s and I did NOT need the shims, as most everyone I have heard does not, It was common to possibly need them on the old yella terras, but these newer ones NO.

djfury05

iTrader: (30)

Pushrod length determines preload not shim height as vettenuts said. Figure out the wipe pattern first using or not using the shims. FWIW I had 7.400 pushrods and .100 preload on my ls7 lifters and it was loud!! I changed to 7.350s and .050 preload and it was almost as quiet as stock.

99Bluz28

iTrader: (35)

Okay, so I set the wipe pattern first to as narrow as possible, centered on valve stem. Then I check my lifter pre-load to verify the optimum push-rod length to use, correct?
So then what's the optimum amount of preload for the LS7 lifters?

racer7088

5/8 to 7/8ths cold will work fine Blur. Usually as Vettenuts said the pattern is better with the supplied washers.

99Bluz28

iTrader: (35)

Would a little more pre-load be better?

racer7088

not a big difference. 3/4 ish seems to work fairly well for noise and performance in general.