The ARP 218-4701 is a professional-grade cylinder head stud kit engineered for high-performance and competition engines. Built from premium 8740 chrome moly steel and heat-treated to 200,000 psi, these studs deliver exceptional strength and reliability for demanding applications.
Key Features:
- Premium 8740 chrome moly alloy rated at 200,000 psi tensile strength
- 12-point head design for improved wrench engagement
- Vertical rack heat-treatment ensures complete and uniform heat penetration
- Centerless ground for precise concentricity and perfect alignment
- Thread rolled after heat-treat for 10x better fatigue strength
- Undercut short studs equalize stretch for consistent clamping force
- Includes hardened parallel-ground washers for even load distribution
Manufacturing Excellence:
ARP's manufacturing process sets the standard for fastener quality. Each stud is precisely heat-treated in vertical racks rather than batch-processed, ensuring consistent properties throughout. The centerless grinding process involves multiple precision cuts to achieve exceptional straightness and concentricity, allowing cylinder heads and gaskets to align perfectly during installation. Thread rolling is performed after heat-treatment, which significantly increases fatigue resistance compared to pre-heat-treat threading methods used by competitors.
Performance Advantages:
Head studs offer significant advantages over traditional head bolts. During installation, studs stretch only along the vertical axis when the nut is torqued, providing more accurate and consistent clamping force. Bolts, by contrast, experience both torsional and tensile stress simultaneously, leading to less predictable loading. The undercut design on shorter studs helps equalize stretch across all fasteners, compensating for head gasket compression and reducing the risk of gasket failure. This results in superior engine sealing and consistent performance.
Installation Notes:
Studs should be installed finger-tight in a relaxed state—never force them in using a jammed nut. Apply torque only to the nut during final assembly. After initial engine operation, re-torque all fasteners to compensate for head gasket compression. The 12-point head design and wide-area flange eliminate the need for valve train removal when retorquing cylinder heads.
Trusted by professional engine builders across all forms of motorsport, ARP Pro Series studs represent the highest quality fastener solution available for competition and high-performance engines.
