3/8 Viton Valve Seals - .500

The 3/8 Viton Valve Seals by MANLEY are precision engine components designed to seal valve stems and prevent oil leakage into the combustion chamber. These seals are essential for any engine rebuild, high-performance modification, or routine valve replacement where reliability and longevity matter. Manufactured to OEM standards, they address the critical need to maintain compression and prevent oil burning—common issues when factory seals wear out or deteriorate over time.

Each set includes eight seals engineered from Viton fluoroelastomer, a synthetic rubber compound rated for sustained high-temperature exposure and chemical resistance found in modern engine environments. The 3/8 inch valve stem diameter and 0.500 inch guide outer diameter sizing ensures precise fitment on compatible valve guides. Viton material offers superior durability compared to traditional Buna-N seals, resisting degradation from heat cycling and maintaining elasticity across extended operating ranges typical of street and performance applications alike.

Rebuilders, machine shops, and performance enthusiasts rely on MANLEY valve seals to restore engine integrity during top-end work. Installation occurs during valve guide preparation—seals are pressed onto the guide bore to create a dynamic seal around the valve stem. Proper fitment depends on matching both the stem diameter (3/8 inch) and guide OD (0.500 inch) to your engine's specifications; verify compatibility with your vehicle's manufacturer documentation or consult a technician before purchase to ensure correct application.