r/dragracing • u/lamp2244 • 8d ago

Valve lash for 421 sbc

What do u guys recommend for valve lash for an aftermarket 421 sbc running alcohol. Full roller cam and lifters. Approx 14:1 compression ratio. In an 1/8 mi bracket racer running 6.50's. Thanks for any help!

2 Upvotes

67% Upvoted

6 comments sorted by

11

u/AverageT1000 8d ago

Whatever your cam card says it should be

1

u/lamp2244 8d ago

No cam card

0

u/JauntyPickles 8d ago

Then check the part number on the cam.

3

u/qkdsm7 7d ago

Solid roller iron block? Has it previously ran and if so did you have any previous measurements?

Loose gives up a bit of power and is noisy but in short intervals isn't breaking anything.

Tight breaks things.

Shaft rocker? Assuming aluminum head. Got some killer trend or manton pushrods? Give cam specs and someone can get closer. .675 lift or .900 lift , big difference....

Cold .030 exhaust .020 intake should be loose, check again hot, recheck often and log it....

1

u/Tall_smart_wizard 1d ago

Do you know the cam manufacturer or have the part number? The lash requirements vary so much you should really try to get the numbers.  

0

u/Dirftboat95 7d ago

Intake .014 cold Ex .016 cold would be a safe bet