not sure, I have a roller block that uses stock magnum hyd roller lifters. That cam is .560/.565 seems to be doing just fine. The other engine is a magnum block with Solid roller lifters and that cam is .640/.645 lift, Comp 8043-16 lifters.
I have seen a lot of crate engines in that .560-.570 range as well with no known issues. I did ask Howard cams about it a for cam in that range, and this was their direct quote to me. "That would be the upper limit on that lifter. Our part #91713 will handle higher lift, spring pressures & RPM."
