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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.
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 (a very common industry practice). It costs a lot more to do it this way, because it's tough on tooling, but the results are well worth the extra effort.
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!
Premium quality heat-treated 8740 chrome moly steel head stud kits are available for most every domestic and import applications. You won't find a better quality stud on the market from any other source. Look for ARP stamped on each stud as your assurance of quality
Installation Tips:
- Clean and chase all bolt threads in block to ensure proper thread engagement and accurate torque readings.
- All hardware should be cleaned and inspected for possible shipping damage prior to installation.
- Since most studs extend into the water jacket, coat threads with ARP thread sealer and screw in hand tight ONLY.
- Install gasket and head, then lubricate washers and nuts with oil or ARP moly assembly lubricant prior to their installation.
- Following the engine manufacturer's torque pattern, torque each stud nut three times to recommended values found in the general fastener chart below.
NOTE: To ensure positive sealing of "wet" head studs, a hardening or semi-hardening sealant, such as Loc-Tite or Permatex, etc. should be used. Some engine builders employ a sealer in the coolant, such as Aluma-Seal, Silver Seal or K&W sealer, etc. You may also use high temperature RTV silicone. Whatever product is used, it is imperative that the cylinder head is installed and torqued to proper levels BEFORE THE SEALANT HAS CURED!
| 6mm stud | 10 | 9 |
| 8mm stud | 25-32 | 20-25 |
| 10mm stud | 54-68 | 42-53 |
| 11mm stud | 80-100 | 63-79 |
| 12mm stud | 97-122 | 77-96 |
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