Built for the Toyota Cressida, obtaining the optimum cylinder head-to-block sealing is especially critical in small displacement engines employing high compression pistons or power adders like turbochargers, nitrous oxide, and superchargers.
ARP head studs are popular among leading Sport Compact/Import racers because ARP uses a premium grade 8740 alloy rated far superior to 'aircraft' quality.
Each stud is precisely heat-treated to 200,000 psi, and following heat-treat, each stud is centerless ground to make it as close to perfectly concentric as possible.
This procedure involves about ten very slight cuts and results in an exceptionally straight part.
Lesser quality studs are not even centerless ground; the material is thread rolled in bar stock form mostly before heat-treat, when the material is easier to machine.
Because ARP studs are manufactured to such exacting tolerances, gaskets and cylinder heads literally glide into position and are perfectly aligned, something that won't happen with inferior quality head studs.
ARP studs are thread rolled after heat-treat, which gives them about 1000% (that's ten times) better fatigue strength than those studs that are threaded prior to heat-treat.
ARP also offers specially undercut studs for several engines.
This procedure, done only to the shorter studs, more equalizes the 'stretch' of both studs, which makes for a more consistent clamping force that compensates for head gasket compression when the head is installed.
This helps prevent blown head gaskets and assures optimum sealing.
