ARP 123-4003 Cylinder Head Stud Kit Chrome Moly Steel - 8740

The ARP 123-4003 is a professional-grade cylinder head stud kit engineered for high-performance and racing applications. Constructed from premium 8740 chrome moly steel, these studs are heat-treated to 200,000 psi tensile strength, providing exceptional clamping force and reliability under extreme conditions.

Key Features:

• 8740 chrome moly steel construction rated at 200,000 psi tensile strength
• Vertical rack heat-treatment process ensures complete and uniform heat penetration
• Centerless ground after heat-treat for precise concentricity and straightness
• Thread rolled after heat-treatment for 10x better fatigue strength compared to pre-heat-treat threading
• Hex head design for convenient installation and torquing
• Includes hardened parallel-ground washers for even load distribution
• Undercut studs (where applicable) equalize stretch for consistent clamping force

Why Choose Studs Over Bolts:

Head studs provide superior clamping accuracy compared to bolts because they stretch only along the vertical axis when torqued, eliminating the twisting forces that affect bolts. This results in more consistent torque loading and better head gasket sealing. Studs also simplify engine assembly by allowing cylinder heads and gaskets to align properly and glide into position effortlessly.

Installation Notes:

Install studs finger-tight in a relaxed mode—never force them in with a jammed nut. Apply torque only to the nut, allowing the stud to stretch uniformly. Re-torque after initial engine run-in to compensate for head gasket compression.

ARP Pro Series fasteners are trusted by professional engine builders worldwide for competition powerplants where failure is not an option. Each stud is manufactured to exacting tolerances and stamped with the ARP logo as assurance of quality.