Melling high performance oil pumps provide dependable performance every time in every application under the toughest RPM conditions. High volume performance upgrade for the M-99HV-S. The 10990 is a big block style oil pump made to fit the small block applications. The drive and idler shafts have been extended to allow for additional support in the cover. Additional support eliminates dynamic shaft deflection at increased RPM levels. The cover is doweled to the pump housing to assure alignment of the shaft bores. The relief valve has a screw-in plug instead of a pin. The housing and cover are CNC machined and phosphate coated. An additional spring, the original stock replacement is supplied which will reduce bypass pressure if needed. Includes 12550 chrome moly intermediate shaft with steel guide. Built with billet steel gears. Every Melling high performance oil pump is individually tested for pressure and flow under actual engine operating conditions.