ARP Head Bolt Kits | Multiple Oldsmobile Fitments (180-3600)Head Bolt Kit by ARP ARP High Performance Series head bolt kits are tough. They are rated at 180,000 psi 15 percent stronger than Grade 8 fasteners. They come available with a reduced wrenching hex head or 12 point head that help eliminate the need for valvetrain removal when re torqueing cylinder heads. Features Fastener Style: Bolt Thread Size: 7 16 in. 20 Undercut Stud: No Head Style: Hex Fastener Material: Chromoly Fastener Finish: Black oxide