S/S Header Bolt Kit - 3/8 x 1.00 UHL (12)

The S/S Header Bolt Kit - 3/8 x 1.00 UHL (12) from ARP is the fastening solution serious engine builders and performance mechanics rely on when assembling high-heat exhaust manifolds and headers. Whether you're building a street engine, prepping for track duty, or restoring a classic with modern upgrades, header bolts endure extreme thermal cycling and vibration that standard hardware simply cannot handle. This 12-piece kit ensures you have matching fasteners throughout your header installation, eliminating mixed metallurgy and potential failure points under load.

ARP's stainless steel construction resists corrosion and maintains clamping force across repeated heat cycles, a critical advantage over mild steel alternatives that gall, seize, or lose preload in the exhaust manifold environment. The 3/8-inch diameter and 1.00 UHL (under head length) specification ensure proper engagement with OEM or performance header flanges without bottoming out or creating compression losses. Stainless steel fasteners distribute load more uniformly than inferior plating, reducing the risk of gasket leakage or bolt stretch—common problems that compromise air-fuel mixture and power delivery on turbocharged or naturally aspirated builds alike.

Mechanics and engine enthusiasts installing cast or fabricated headers on LS, small-block Chevy, Ford, or Mopar platforms benefit from the consistency and reliability this kit delivers. Use these bolts whenever header gaskets are replaced, during engine rebuilds, or when upgrading to performance manifolds on street and race vehicles. Torque to manufacturer specifications for your particular application—proper fastener preload is essential for maintaining gasket seal integrity and preventing exhaust leaks that rob horsepower and increase emissions. This kit covers one complete header assembly or serves as a reliable replacement set for catastrophic fastener failure.