What valves are you using?
Vortec valves have a .290" valve tip for self aligning rocker arms. Standard SB Chevy valves have .250" valve tips. If you use standard SB Chevy valves, self aligning rocker arms will contact the keepers.
I had to use Manley 11863-1 (E) 1.600" and 11860-1 (I) 1.940" valves and self aligning rocker arms. Ferrea does not have SB Chevy valves with a .290" tip. You must use Ferrea valves for a 351-C Ford.
Do not machine the Vortec valve spring pockets. They are too thin, use +.050" keepers to gain valve spring height. My heads have exhaust valve spring rotators which presents a special problem on the exhaust valves. I had to use .075" shims and + .050" locks " on the exhaust valve springs to get 1.750" assembled height. No problem with standard locks on the intake valve springs.
I am also using Comp Cams 26918 beehive valve springs. I enlarged the stock spring seat diameter from 1.250" to 1.320" in order to fit the Comp Cams beehive valve springs. I was even nervous about doing that.
Last edited by MouseFink; 12-29-2012 at 05:39 PM.