Header Bolt Kit - 12pt. 3/8 x .750 UHL (16)

The Header Bolt Kit – 12pt. 3/8 x .750 UHL (16) from ARP is a precision fastening solution engineered for high-performance engine builders and serious automotive enthusiasts working on big-block Chevy and Ford platforms. This 16-piece set addresses a critical need in engine assembly: reliable, consistent fastening where header integrity directly impacts exhaust flow and engine longevity. Whether you're rebuilding a vintage muscle car engine or constructing a modern performance platform, proper header bolts prevent leakage, vibration-induced loosening, and catastrophic fastener failure under extreme heat and cylinder pressure cycling.

Manufactured from chromoly steel with a black oxide finish, the Header Bolt Kit delivers superior strength-to-weight ratio and corrosion resistance compared to standard grade fasteners. The 3/8-inch diameter with 0.75-inch under-head length (UHL) specification ensures proper clamping force distribution across header flanges without interference with exhaust manifold geometry. The distinctive 12-point head design provides multiple grip angles for socket engagement, reducing fastener rounding and enabling precise torque application during initial assembly and future maintenance. Black oxide coating not only protects against rust in the high-temperature exhaust environment but also reduces galling during installation—critical when working with aluminum or cast-iron header materials.

Engine builders, performance shops, and dedicated gearheads benefit most from this fastener kit, particularly those seeking OEM-quality replacement or original assembly hardware for big-block engine work. The set of 16 bolts covers a complete header installation on most V8 configurations, eliminating the need to source fasteners individually. Installation requires standard metric or SAE sockets sized for 12-point heads; torque specifications should follow your engine builder's recommendations, typically 25–35 ft-lbs depending on material interface and assembly sequence. Compatibility is assured for big-block Chevy and Ford applications where header bolt specifications call for 3/8-16 thread pitch and chromoly construction.