Big Twin Evolution tappet blocks do not have counter-bored bolt holes; therefore, when a tappet block is removed (or even just loosened) it should be reinstalled using an alignment tool to ensure that the lifters track properly on the camshaft This tool makes the process quick and easy, ensuring the durability of your installation Also aligns Twin Cam oil pump to the cam support plate; two tools required. TOOL TAPPET BLK ALIGN