Competition Cams 812-16 High Energy Hydraulic Lifters for Small and Big Block Chevy .842 diameter; 94g weight; 1.99 seat height Patented orifice metering valve precisely meters oil to the rocker arms Continuous contact between metering valve and hardened pushrod seat is maintained, eliminating excessive oiling at high engine speeds Contain a longer piston than conventional hydraulic lifters, which provides more load bearing surface and increases lifter longevity Lightweight check valve disc allows for quicker response and maintains added control at all engine speeds and loads