ARP 134-4309 Pro Series Cylinder Head Stud Kit Chrome Moly - 8740 12-Point

ARP 134-4309 Pro Series Head Stud Kit

The ARP 134-4309 is a professional-grade cylinder head stud kit engineered for high-performance and competition engines. Manufactured from premium 8740 chrome moly steel and heat-treated to 200,000 psi tensile strength, these studs deliver superior clamping force and reliability under extreme conditions.

Key Features

• Premium 8740 Chrome Moly Steel: Heat-treated to 200,000 psi for exceptional strength and durability
• 12-Point Head Design: Provides superior grip and allows precise torque application
• Centerless Ground: Each stud is precision-ground after heat treatment for near-perfect concentricity and straightness
• Thread Rolled After Heat Treatment: Delivers 10x better fatigue strength compared to pre-heat-treat threading
• Undercut Design: Shorter studs feature strategic undercutting to equalize stretch and provide consistent clamping force
• Complete Kit: Includes hardened parallel-ground washers for even load distribution and accurate torque readings

Why Choose Head Studs Over Bolts

Head studs provide superior performance compared to conventional bolts. Unlike bolts, which experience both torsional and tensile stress during installation, studs are installed finger-tight and only stretch along the vertical axis when the nut is torqued. This results in more accurate and consistent clamping force, better head gasket sealing, and easier engine assembly.

Manufacturing Excellence

ARP's manufacturing process sets the industry standard. Each stud is vertically rack heat-treated to ensure complete and uniform heat penetration throughout the material. The subsequent centerless grinding process involves approximately ten precision cuts, creating exceptional straightness and allowing cylinder heads and gaskets to align perfectly during installation.

Installation Notes

Studs should be installed finger-tight in a relaxed state—never cranked down with a jammed nut. Always re-torque fasteners after initial engine break-in, as head gaskets will compress during the first heat cycle. The wide-area flanged design allows for cylinder head retorquing without valve train removal.

Application: Pro Series competition-grade fastener system
Material: 8740 chrome moly steel
Tensile Strength: 200,000 psi
Head Style: 12-point
Includes: Hardened parallel-ground washers