Any Chevy engine, if it's well-modified or just slightly warmed-over, requires a good set of valve seals. Originally, a small rubber O-ring, fitted in the second valve stem groove, served as the ...

This 1992 Chevrolet Corvette has the valvetrain of its LT1 engine repaired with a new seat of valve stem seals from Street & Performance - Vette Magazine ...

The loose tolerances allow the valve stem to move laterally in the guide, which quickly oblongs the rigid PC seal and allows excessive amounts of oil to enter the combustion chamber past the valve.