With MOPAROFFICIAL'S contribution of .600, that means say you ran in the middle of the lifter at .050 which at the valve is .075, less some for angularity. Then .600 less .075=.525 valve lift.... for zero clearance. if the lifters pump up the remaining .045 which is .068 less angularity say .008 leaves, .060. So you have to allow an additional .060 in case it happens. Now we are down to a gross lift of .525 less .060 =.465. But what if the valves with the lifters fully pumped up, still have enough inertia to bounce over the nose another .010? now yur down to .455.
Now, I don't think this scenario would ever happen in reality........... but what if it did?
The other scenario with just .020 lifter preload, which being .030 at the valve comes to .600 less .030= .570 allowable valve to piston for zero clearance. Putting proper springs on eliminates or more or less eliminates pump-up, but it's still a good idea to allow some room. Throw in .030 for that, and the max lift becomes ~.540
Lessee .540 or .455 .....................
I'll take proper springs and shorter pushrods for $4000 saved, Mr.Trebec
