COMP Cams™ offers a complete line of valve stem seals, from thestock GM o-ring to the positive-stop Teflon seal. These seals are a mustto keep unwanted oil from entering the combustion chamber throughthe clearance in the valve guides. The o-ring seals use the standardretainer and oil splash shield. The umbrella seal is normally used whena larger-than-stock diameter spring is used, and in the case of a doublespring, the positive-stop Teflon seal is used. We also have a smallerdiameter Viton seal available for triple spring applications. Both the oringand the umbrella seals require no machining, but with the Teflonseal it is necessary to disassemble the heads and machine the top ofthe guide with a special cutter, which can be found above. Wheneveryou are planning an engine overhaul or a cam change, don’t forget thevalve seals.