bracketracer

I'm was checking pushrod lenght last night and with the pushrods I have (7.40), the lifter preload was .080 on the intake and .100 on exhaust. Is it ok to shim up to the rocker stands on stock rockers to achieve to desired .050 - .075 preload?

Jon@Texas-Speed

iTrader: (18)

You'd be better off exchanging the pushrods for the correct length. If you are confident on your measurements, I would get a 7.375" and be done with it. It's easier to get the correct ones than trying to shim them and make sure the swipe on the valve tip is still good IMO.

Jon

PREDATOR-Z

Basically, with non adjustable rockers, preload is reduced by shortening the push rods. Shimming rocker stands will result in geometry change.

bracketracer

Exchanging them would be nice if I had the receipt. Not an option in this case. I'll check the wipe pattern with a .025 shim and make a decision on what to do.

vettenuts

iTrader: (4)

I would check the wipe with no shim first and then with a shim. However, from speaking with a few builders they have stated that aftermarket cams and stock rockers typically require a reduction in height to aid with proper geometry. I also think your preload is fine as is since every stock engine I have checked has come near 0.100" of preload.

KCS

iTrader: (20)

Not a good idea, especially with the stock rocker arms. If you want to get the preload down, you really should order the correct length pushrods and sell the old ones. You'll be glad you did.

bracketracer

Well, I guess we have a differance in opinion here. What happens with .100 preload verses .075? Just curious....

PREDATOR-Z

.100 is within accepted range on stock lifters.

BES Stroked Nova

iTrader: (24)

I use some shims(forget how much they were) under my rockers with the advice from my engine builder that it would it swipe better.

thats on l92's with stock rockers, and I turn 7500+ every pass... so check the swipe and go from there....

BES Stroked Nova

iTrader: (24)

ahhh figured it out, I know why we shimmed up, we ended up milling the heads .075" to get some compression out of the stock dished pistons... but we were looking for proper swipe reason we shimmed, then ordered the proper pushrods.

vettenuts

iTrader: (4)

Milling the heads doesn't alter rocker geometry.

bracketracer

Thanks for all the info. Checked PTVC last night and no problem there. Over .300 clearance on both. I'll wait until I torque the heads down with the new gaskets and check the pushrod length again just to make sure.