djoif3

So I called Comp and they said that these run about 8-10 thousandths preload. But that perfect preload would be .005 So how would I obtain .005? I read somewhere that it is about 1/8 turn. Does anyone know for sure? I did ask him if I needed adjustable rockers and he said no.

Jontall

This is right from Comps website:
NOTE: These lifters require an adjustable valve train (check here for adjustable valve train components), and must be pre-loaded to .002" to .004" for proper operation!

djoif3

Thats weird,, because im looking at comps site and dont see anything about that. whats the url your looking at??

Jontall

You said type R.
http://www.compperformancegroupstore...de=GEN3Lifters

djoif3

That is somewhat contradicting. These are the same lifters. The lifter PN# I have is 875-16, meaning 16 QTY and the PN# u show is 875-1, meaning 1 QTY. Im talking about comp being contradicting. Kinda weird on Comps part.

therabidweasel

iTrader: (5)

I set them up for 0.030 cold. You lose 0.007 from differential thermal expansion between the pushrod and block. I measured preload for every pushrod in my engine several times, and the peak to peak variation was 0.020. Thats using cylinder specific rocker shims and rockers. Tony Mamo has told me he believes most of the variation is in the rocker cup height. Custom rods come in 0.005 increments with a +/- 0.0025 tolerance. It took 5 different custom lengths to cover my engines range and I believe I had about 0.007 of total preload variation by the time I was done. If you dont go adjustable you need to be very persnickety.

Jontall

You're going to need adjustable rockers for these lifters.

moeZ28

iTrader: (7)

You don't need adjustables...I set mine up on my old TREX cammed car in my sig at 0.030" cold with stock rockers and had the quietest valvetrain around. They are great lifters and will work with the right preload on stock rockers.

kenp

iTrader: (9)

They are reduced travel lifters. I've been running them for five years. 1/8 TO 1/4 Turn after zero lash. You do need adjustable rockers. They are not quiet when they are set up according to spec.

If you do not follow manufacturer instructions you do it at your own peril.