ARP Pro Series Head Bolts
ARP Pro Series bolts are cold-forged to maintain molecular integrity, heat-treated prior to thread rolling and machining, and adhere to the ARP ZERO defect - ZERO failure quality standard. These head bolt kits are application-specific and engineered to provide the superior strength found in competition engines.
Pro Series kits are available in two materials: the standard 8740 with a 190,000 psi tensile strength rating and the proprietary ARP2000, offering a 220,000 psi tensile strength where noted. All Pro Series head bolts feature either a reduced wrenching hex or 12-point head, as well as a wide-area flange. This design allows for larger diameter valve springs and eliminates the need for valve train removal when retorquing the cylinder head.
Each kit includes hardened parallel-ground washers for uniform load distribution. Additionally, many applications feature undercut short bolts, which help eliminate head gasket failures by providing more stretch, compensating for additional gasket compression.