COMP Cams Tools 5010 Developed by one of the top NASCAR engine builders, this innovative tool precisely grooves the lifter bore to ensure the pressure fed oil is directly injected into the contact area between lifter and camshaft. This increased oiling significantly reduces wear on the camshaft and lifters and decreases the risk of premature failure during break-in. This machine operations to the block is quick, easy, inexpensive and is the best insurance for a new cam. Grooving ToolS, Lifter Bore COMP Cams Lifter Bore Grooving Tool for .842", .874" and .904" Diameter Lifters CldrHd ResurfMachine