ARP 207-4203 head studs kit Mitsubishi Lancer Evo IV, V, VI, VII, VIII, IX, Eclipse 4G63T M11 (8740 Cro-Mo)

For: Mitsubishi Lancer Evo IV, V, VI, VII, VIII, IX with 4G63T engines

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 190,000 psi.

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. It’s important to note that 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).

You will also note that ARP® 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—and one that compensates for head gasket compression when the cylinder heads are installed. This helps prevent blown head gaskets, and assures optimum engine sealing