Solid lifters use either the shouldered studs or the 7/16 studs, but you MUST use Poly-Locks. I use the 7/16 BBC studs for both my 428 and 455. The 455 has a solid lifter cam; the 428 has hydraulic lifters. I adjust the poly-locks on the hydraulic cam to allow for slight wear compensation by going one full turn after the push rod no longer spins by hand. This also won't allow them to pump up too much at high RPM. They require re-adjustment when I start to hear them make a little noise. I adjust the Solid lifter lash per the cam maker's specs.
