These hydraulic tappets feature numerous significant design improvements and are perfect for stock replacement as well as high performance applications. A 3.12mm larger inner bearing race reduces stresses to increase axle, bearing, and roller life. A redesigned plunger assembly better withstands forces associated with heavy-duty valve springs and cams typically used in high-performance applications. Another feature is a revised metering device which precisely controls oil delivery to top end, insuring rapid lifter pump-up and reducing possibility of oil starvation to bottom end. Each lifter body and plunger assembly is hand-fit and then pressure-tested to insure correct operation.