chris-m

i've had my heads away for a clean up/check while i am rebuilding my bottom end, and the company concerned are advising a very light skim to clean the head faces up ie 4 or 5 thou' max.

while this isnt a lot, will it have any noticeable effect on pushrod length and compression?

engine is a 346 Ls6 block, deck height was i think 9.222" and the cam is a comp cams grind 220/220 111lsa with very mild lift around .510"

currently i have only got comp cams pushrods in sizes 7.4" and 7.425" plus the stock o.e pushrods to use, so wondering which set is likely to be needed?
i swapped from 7.40" to 7.425" to quieten down the valvetrain and the preload was about right using them, will they be too long now or is 4-5 thou head skim not noticeable?
thanks

The Alchemist

iTrader: (19)

Well, if you take that 4 or 5 thousandths off the pushrod length, you get a 7.420" puhsrod, which unless you have them custom made, isn't available. The lifter will be able to take up the extra preload and you'll be fine.

chris-m

so stick with the 7.425s you reckon rather than go back to 7.40s? i'm fitting new ls7 lifters and new lifter trays as a precaution anyway

The Alchemist

iTrader: (19)

Stick with the 7.425s, but check on the use of the ls7's as someone recently told me that the plunger in the ls7 is 60 thousandths higher than the older style lifters. Not 100% sure on that though.

chris-m

will measure them up thanks for that

ShevrolayZ28

iTrader: (4)

If the pushrod length was ok before it should still be ok after 0.005" milling. And FWIW, each 0.006" results in a chamber volume decrease of ~1 cc.

chris-m

ok cheers for that