These hydraulic lifters did not work in two different vehicles. The vehicles had loud tapping/knocking noise in the engine after several miles or breaking in the parts. No good! The problem I found with these lifters is the small hole machined in the casing of the lifter assembly. It would not allow the hydraulics of the lifter to build and hold the oil pressure which in term makes the lifter stiff and holds the push rod firm in place. After teardown of the engine I found most pushrods loose..