This head stud is our choice for big horsepower and high boost applications. This is the only head stud proven to reliably hold heads down over 25psi of boost on our big horsepower builds.
Custom Age 625 Plus: This newly formulated super-alloy demonstrates superior fatigue cycle life, tensile strength and toughness with complete resistance to atmospheric corrosion and oxidation. ARP is the first to develop manufacturing and testing processes for fasteners with Custom Age 625+.
Typical tensile strength is 260,000-280,000 psi. The studs are manufactured in ARP's Santa Paula, CA plant with threads rolled after heat treat to provide optimum fatigue strength. They are center-less ground to ensure perfect concentricity. The ends of the studs are broached to facilitate easy installation. This feature also enables the cylinder head to be removed in tight quarters.
No Modification to your cylinder head or block is required as these are a direct screw-in replacement for the OEM head bolt.
Instructions:
- Torque for 8mm bolts - 25 ft-lbs
- Torque for 12mm bolts - to 50, 85 then 125 ft-lbs in standard torque sequence
- Note 1: Let sit and re-torque each bolt one at a time
- Note 2: Always use assembly lube during install on stud and included hardware
