The original Shovelhead hydraulic tappets are not up to the challenge of high performance applications. High rpm, stronger valve springs, and higher lift cams push them beyond their limits. That‘s why most hot rod Shovels are built with (noisy) solid lifters. S&S billet tappet guides for Shovelheads are similar to Evolution style tappet guides and are designed to use Evolution style hydraulic tappets. These tappets have proven themselves in countless high performance Evolution engines where they reduce valve train noise and required maintenance. They work with Quickee Pushrods which S&S has developed with a new type of adjuster that screws into the pushrod until the threads disengage and the adjuster simply slides into the pushrod making installation or removal a snap.