COMP Cams - 503-16
Valve Stem Seal - Positive Stop - 11/32 in Valve Stem - 0.530 in Guide - PTFE - Set of 16
COMP's Positive Stop PTFE valve seals offer more clearance for dual springs with better sealing than o-ring or umbrella seals. These 503 seals have a .630" outer diameter and fit applications with 11/32" valves and .530" OD valve guides.
COMP Cams offers a complete line of valve stem seals, from the umbrella seals to the positive-stop Teflon seal. These seals are a must to keep unwanted oil from entering the combustion chamber through the clearance in the valve guides. The umbrella seal is normally used when a larger-than-stock diameter spring is used, in the case of a double spring, the positive-stop Teflon seal is used. The umbrella seals require no machining, but with the Teflon seal it is necessary to disassemble the heads and machine the top of the guide with a special .530 diameter cutter. Whenever you are planning an engine overhaul or a cam change, don't forget the valve seals.
