That's usually where they fail from too much cyl. pressure/boost/detonation. We had FelPro HP's on a 340 & ran it up to 21#'s of boost w/water-meth injection, it had higher grade cap screws than stock, and torqued evenly in steps...left to sit & re-torqued 2×. Never blew a gasket again, even when the water injection failed & detonation collapsed a ring land on the TRW blower piston.