31-6307 HVHP oil pump kit with gears. Universal cover

The S&S HVHP (High Volume High Pressure) oil pump kit is the ultimate lubrication upgrade for Evolution-era engines. Sold as a kit, it features a universal cover with multiple plumbing options for custom applications. Originally designed for massive 4-1/8 inch bore engines with piston cooling jets, this pump provides significantly more oil flow than stock, with feed gears that are 9% wider and return gears that are 28% wider. Despite the increased capacity, it maintains the same thickness as a stock pump. This kit includes drive gears, a steel breather valve, and a shim kit. It fits 1984 to 1991 Big Twin models, though the included drive gears are specific to 1984 to 1989 style pinion shafts. It is a vital upgrade for high-performance builds that demand superior cooling and lubrication.