COMP's Positive Stop PTFE valve seals offer more clearance for dual springs with better sealing than o-ring or umbrella seals. These 510 seals have a .600" outer diameter and fit applications with 11/32" valves and .500" OD valve guides.
Available individually under 510-1, available in a set of 16 under 510-12
Engines w/ 0.500" OD Valve Guides and 11/32" Valve Stems