Constructed of high-quality billet aluminum with a polished finish Unique three-valve system delivers 8-10 lb. of oil pressure to the crankshaft at idle (all other oil pumps have a pressure valve that closes at idle, denying the crankshaft oil flow at idle) Stainless steel check valve eliminates wet sumping upon start-up; positively will not leak oil into the lower end during storage No provisions for primary or rear-chain oiling U.S. Patent #6,230,680. OIL PUMP 84-91 BT