ARP head Stud Kit ARP uses a premium grade 8740 alloy that is rated far superior to 'aircraft' quality. Each stud is precisely heat-treated to 200,000psi and centerless ground to make it as close to perfectly concentric as possible. ARP studs are thread rolled after heat treat, which gives them about 1000% better fatigue strength than studs threaded prior to heat treat. It costs a lot more to do it this way, but the results are worth the effort.
NOTE: The stud closest to the exhaust cam gear may contact the distributor shaft. If this happens, the end of the distributor shaft must be ground down to prevent interference or catastrophic damage may result.