Sump Plug - 6 packEliminates blocking the internal engine case scavenge pick up hole The M8 main sump cross port on the inside of the M8 engine case is in a slightly different location & height in each engine case. This cross port is created when the bottom plug hole is machined and tapped by the factory. The machining breaks through the casting wall, creating the sump port. Whereas the Twin Cam engine cross scavenge pick up hole is a machined bore, and is in the same location in every engine case.