hi, the schubecks were meant to be used on flat tappet cams in stock eliminator. that way you can run lots of spring pressure and rev engine way up. also, schubecks do not require break in, and can be swapped from cam to cam. you have to have strong pressures to keep lifter from bouncing on lobes. they will break!!! btw, the cam companies buy their lifters from Johnson lifters, so they are the same.