ARP 185-4001 Cylinder Head Stud Kit Chrome Moly - 8740

The ARP 185-4001 is a professional-grade cylinder head stud kit engineered for high-performance and competition engines. Built from premium 8740 chrome moly steel, these studs are heat-treated to 200,000 psi tensile strength, providing superior clamping force and reliability under extreme conditions.

Key Features:

• Premium 8740 chrome moly alloy rated at 200,000 psi tensile strength
• Vertical rack heat-treatment process ensures complete and consistent heat penetration
• Centerless ground after heat-treat for exceptional concentricity and straightness
• Thread rolled after heat-treat for approximately 1000% better fatigue strength
• Hex head design for reliable wrenching
• Includes hardened parallel-ground washers for even load distribution
• Undercut design on shorter studs equalizes stretch for consistent clamping force

Performance Benefits:

• Superior alignment during assembly—cylinder heads and gaskets glide into position
• More accurate and consistent torque loading compared to bolts
• Reduces risk of head gasket failure through optimized clamping force
• Studs stretch only on vertical axis during torquing, eliminating twisting forces
• Easier engine assembly and serviceability for racing applications

ARP's exacting manufacturing process includes precision centerless grinding with multiple slight cuts to ensure each stud is as close to perfectly concentric as possible. The post-heat-treat thread rolling process, while more expensive and demanding on tooling, delivers dramatically improved fatigue resistance compared to conventional pre-heat-treat threading methods.

Installation Notes:

Studs should be installed finger-tight in a relaxed mode—never crank them in using a jammed nut. Apply torque only to the nut, allowing the stud to stretch solely on the vertical axis. Re-torque after initial engine run to compensate for head gasket compression.

Trusted by top professional engine builders across all forms of racing, ARP Pro Series head studs represent the highest quality fastener solution available for serious performance applications.