ARP 117-5401 Main Bolt Kit for Cadillac 331-365-390 Hex Head

The ARP 117-5401 main bolt kit is engineered for use in classic Cadillac 331, 365, and 390 cubic inch engines from 1949 through 1962. Designed to meet the demanding standards of professional engine builders and high-performance applications, these main bolts provide far superior strength and reliability compared to factory fasteners.

Premium Construction and Materials:

• Forged from 8740 chrome moly steel for exceptional strength and durability
• Heat-treated to 180,000 psi tensile strength in ARP's High Performance Series
• Threads are rolled after heat-treating, providing exponentially better fatigue strength than pre-threaded bolts
• Reduced wrenching head design for improved clearance during installation
• Large underhead radius distributes clamping load evenly and reduces stress concentrations
• Hex head configuration for positive wrench engagement

Complete Kit Includes:

• Hardened parallel-ground washers for uniform load distribution
• All necessary fasteners for complete main cap installation

ARP main bolts help prevent main cap walk and fretting while protecting engine block threads. These precision-manufactured fasteners are essential components for any performance rebuild or racing application involving early Cadillac V8 engines.