Melling high performance oil pumps provide dependable performance every time in every application under the toughest RPM conditions. Standard volume performance upgrade for M-83. Gerotor set assembled to an extended drive shaft that allows for additional support in the cover. Supporting the drive shaft in both the housing and cover eliminates dynamic shaft deflection at increased RMP levels. The cover is doweled to pump housing to assure alignment of shaft bores. The housing and cover are CNC machined and phosphate coated for wear and rust prevention. The relief valve has a pressure adjustable screw-in plug instead of a cup plug. Every Melling high performance oil pump is individually tested for pressure and flow under actual engine operating conditions.