ARP 291-5801 Main Cap Fasteners - 4-Bolt Main Stud Kit with 12-Point Nuts

The ARP 291-5801 main cap fastener kit provides high-strength engine block reinforcement for 4-bolt main applications. This complete kit includes precision-manufactured main studs, 12-point nuts, and hardened parallel-ground washers for maximum clamping force and reliability.

Key Features:

• Manufactured from 8740 chrome moly steel for superior strength and durability
• Heat-treated in-house to 200,000 psi tensile strength
• Precision J-form threads rolled after heat-treat for 1000% stronger threads than conventional fasteners
• 12-point nut design for easier installation and more accurate torque application
• Hardened parallel-ground washers included for optimal load distribution
• 4-bolt main configuration for maximum main cap stability

Performance Benefits:

• Eliminates main cap walk and fretting under high loads
• Protects engine block threads from damage during repeated installations
• Provides consistent clamping force across all main caps
• Essential upgrade for high-performance and racing applications

ARP main studs offer superior thread engagement and clamping characteristics compared to conventional bolts. The stud design allows the fastener to be installed and properly torqued without twisting, ensuring accurate preload every time. Each kit arrives complete with all necessary hardware for a professional installation.