COMP Cams Positive Stop Valve Stem Seal - 3/8 in Valve Stem - 0.500 in Guide - Steel Body / Viton - Set of 16 521-16 29020BK including GM

including GM

GM / Ford / Lincoln / Mercury

but with a more rigid wheel and Bead-Loc design to hold up to the rigors common to East Coast Modifieds

Metal internal and external retainer provides a reliable & reusable fuel connection that cannot snap loose or melt like some plastic retainers

COMP Cams Positive Stop Valve Stem Seal - 3/8 in Valve Stem - 0.500 in Guide - Steel Body / Viton - Set of 16 521-16 29020BK including GMProviding the best sealing properties and spring clearance, Viton valve seals are an excellent choice in performance applications. The 521 seals have a . 545" OD and fit applications with 3 8" valves and . 500" OD guides. The COMP Cams philosophy has never changed: make the highest performing products possible and lead the industry in technological development. One thing COMP Cams has never forgotten: Performance is defined by what happens out on the