Valve Stem Oil Seals, Metal Body Viton Seal 529-16 CO529-16 Suit 11/32" Valve, .530" Guide .675" O.D VALVE STEM OIL SEALS, 11/32" COMP Cams offers a complete line of valve stem seals, a must to keep unwanted oil from entering the combustion chamber through the clearance in the valve guides. The o-ring seals use the standard retainer and oil splash shield. The umbrella seal is normally used when a larger-than-stock diameter spring is used, and in the case of a double spring, the positive-stop Teflon seal is used. Smaller diameter Viton seals are also available for triple spring applications. Both the o-ring and 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 cutter, which can be found to the left side of this page.