ARP 135-3609 Cylinder Head Fasteners 8740 Chrome Moly Hex Head Bolt Kit

The ARP 135-3609 Cylinder Head Fasteners are precision-engineered high-performance head bolts designed for demanding automotive applications. These fasteners are manufactured from premium 8740 chrome moly steel and heat-treated to 180,000 psi tensile strength—15% stronger than Grade 8 bolts—providing exceptional clamping force and reliability for high-performance and racing engines.

Key Features:

• Premium 8740 chrome moly steel construction with 180,000 psi tensile strength
• Hex head design with reduced wrenching profile and wide-area flange
• Allows cylinder head retorquing without valve train removal
• Thread rolled after heat treatment for superior fatigue resistance
• Includes hardened parallel-ground washers for even load distribution
• Precision centerless ground for exceptional straightness and alignment
• Vertical rack heat treatment ensures complete and consistent heat penetration

Manufacturing Excellence:

ARP employs rigorous manufacturing processes that set these fasteners apart. Each bolt is vertically heat-treated in special racks to ensure uniform properties throughout, then centerless ground through multiple precision cuts to achieve near-perfect concentricity. The threads are rolled after heat treatment—a more expensive process that delivers approximately ten times better fatigue strength compared to pre-heat-treat threading used by other manufacturers.

Installation Benefits:

The precision tolerances of ARP fasteners allow cylinder heads and gaskets to align effortlessly during assembly. The reduced hex head design accommodates larger diameter valve springs while the wide-area flange eliminates the need for separate washers in most applications. These bolts provide more accurate and consistent torque loading compared to conventional fasteners, ensuring optimal head gasket sealing and long-term reliability.

Complete kit includes all necessary fasteners and hardened washers for installation. Ideal for street performance, racing, and engine rebuilding applications where superior strength and reliability are essential.