I'm mocking up my SBC valvetrain and have a few questions I thought you guys might be able to help with:

1) I'm mocking it up with no head gasket. To determine optimum pushrod length, do I add the full compressed thickness of the head gasket to the pushrod length obtained with no gasket?

2) I've got almost zero clearance between the pushrod and the cylinder head at the right at the valve cover rail. How much clearance do I need here? The pushrod is well-centered and has plenty of clearance starting about 1/4" down from the valve cover rail.

3) My motor will have a 7,500 rpm redline, shaft rockers, and 220/560lb. springs. Will a 5/16" pushrod live in this application? Stepping up to a 3/8" pushrod will require lots of grinding.

Thanks. -Neil

1) Yes, add the compressed gasket thickness. You will typically find that pushrod lengths are available in 0.050" increments, so you might end up just adding 0.050" to your length without the gasket.

2) Hmm. not sure on small blocks. I would imagine 0.060" would be a desired clearance however. Might need your die grinder..

3) Quality one-piece, 0.080" wall thickness, chrome moly pushrods from a reputable brand should be OK. You may wish to get advise from the manufacturer because I'd say your boardering on what may to too much spring pressure for a 5/16" (solid roller?), and you may need to step up to 3/8" for reduce flex and stability. -3/8" won't be a heap of added weight over the 5/16" either.