8mm LS Steel & Viton Dual/Single Spring Valve Stem Seals (Suits: 0.500" Guides) If it has to seal

If it has to seal right the first time Speedmaster has what you need

Upgrade your GM Powerglide or TH400 for extreme horsepower applications with this big shaft stator tube kit

These Speedmaster Copper collector gaskets are about as close to blow-proof as you can get

this stand blends seamlessly into your life

and 3/8 in

8mm LS Steel & Viton Dual/Single Spring Valve Stem Seals (Suits: 0.500" Guides) If it has to sealValve stem seals control the lubrication of the valve stem as it slides in the valve guide. Too little oil causes stem and guide wear. Too much oil increases oil consumption and can cause a buildup of carbon, leading to valve seat damage and early valve grind. Speedmaster valve seals are posi stop seals made from high temperature Viton material for a long lasting seal.