ARP uses a premium grade 8740 alloy that is rated far superior to "aircraft" quality. Then, each stud is placed vertically in special racks and precisely heat treated to 190,000psi. This procedure ensures complete heat penetration and the results are far superior to those lesser quality studs from other manufacturers who just dump pieces in a basket and hope for the best. Following the heat treat, each stud is center-less 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. It's important to note that lesser quality studs are not even center-less 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, you will note that gaskets and cylinder heads literally glide into position and are perfectly aligned.
ARP studs are thread rolled after heat treat, which gives them about 1,000% better fatigue strength than those studs that are threaded prior to heat treating. It costs a lot more to do it this way, because it's much tougher on tooling, but the results are well worth the extra effort.NOTE: Some ARP Head Studs are special orders. It will take 1-2 weeks to get.
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