Ghost's68

iTrader: (1)

All,

I am finishing up my full bolt on LS3 going into a 68 C-10. I got my heads that were milled to have a CC of 68.5cc , Pat G custom spec cam ground by TSP, new LS7 Lifters, new LS3 head gaskets. Block is the SBE.

I used the OE/IC method to find the cam base circle, pushed the lifters on the cam, placed comp checker turned in 9 turns on lifter, bolted down rocker and still had play, turned to 10 full turns and was tight. Turned to 9.5 and had slight play. Turned to 9.75 and got zero lash.

So math goes as:
9.75x.050= .4875
6.8+.4875=7.2875 pushrod length
7.2875+.070 preload = 7.3575

A buddy of mine suggested I go with the 7.35 PR instead of running higher preload if I jumped up to 7.375. Am I right in my math? TIA

ColeGTO

iTrader: (3)

Math looks correct.

However, I'd still purchase a cheap 12" caliper and measure the pushrod to be safe. Or see if someone has one you can borrow.



Cole

tjz450

You really need a digital caliper. The 6.8 collapsed length of the checker was pulled from advertising. And I doubt the .050" per turn is perfectly perfect either. So you've introduced two possible errors. Check out iGage brand of calipers online, I paid less than 30 for my last one. I'm not sure why such precision is needed when every PR will be different if we wanted exact .0XX preload on each and every lifter.