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For openers, ARP uses a premium grade 8740 alloy that is rated far superior to “aircraft” quality. Each stud is placed vertically in special racks and precisely heat-treated to 200,000 psi. 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 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). 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 – 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 (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 .
- 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.
- Clearly, ARP Head Stud/Bolt Kits are the best on the market today, and the favorite of leading professional engine builders in all forms of racing.
HIGH PERFORMANCE SERIES
High Performance head bolts are available with a reduced wrenching hex or 12-point and wide area flanged head that eliminates the need for valve train removal to facilitate cylinder head retorquing. All High Performance Series bolts are 180,000 psi (which is 15% stronger than Grade 8) and kits come complete with hardened parallel-ground washers.
PRO SERIES
All Pro Series bolts are cold-forged to ensure molecular integrity, heat-treated prior to thread rolling and machining, and are rated nominally at 200,000 psi. ARP Pro Series head bolt kits are application specific – designed for use with typically competition only components. These fasteners deliver superior strength and meet the ARP “ZERO defect – ZERO failure” quality standard. Hardened and parallel-ground washers are included with each kit to ensure even load distribution and accurate torque readings. All Pro Series head bolts have a reduced wrenching hex or 12-point head and wide area flange to eliminate the need for valve train removal for cylinder head retorquing and permits the use of larger diameter valve springs. Most applications have undercut short bolts that can help eliminate head gasket failures through providing more “stretch” to compensate for the additional compression of gaskets.
Head Studs vs Bolts
On many street-driven vehicles, where master cylinders and other items protrude into the engine compartment, it’s probably necessary to use head bolts so that the cylinder heads can be removed with the engine in the car.
For most applications, however, studs are recommended. And for good reason. Using studs will make it much easier to assemble an engine (especially a racing powerplant which must be serviced frequently and quickly!) with the cylinder head and gasket assured of proper alignment.
Studs also provide more accurate and consistent torque loading. Here’s why. When you use bolts to secure the head, the fastener is actually being “twisted” while it’s being torqued to the proper reading. Accordingly, the bolt is reacting to two different forces simultaneously. A stud should be installed in a “relaxed” mode – never crank it in tightly using a jammed nut.
If everything is right, the stud should be installed finger tight. Then, when applying torque to the nut, the stud will stretch only on the vertical axis. Remember, an undercut shorter stud will have a rate similar to a longer, standard shank stud. This provides a more even clamping force on the head. Because the head gasket will compress upon initial torquing, make sure studs and bolts are re-torqued after the engine has been run.
Products that have an availability of "In Stock" are shipped same day or the next if ordered before 2 PM EST. Products that have an availability of "Manufacture Ship" are products that ship directly from the manufacture and usually ship within 2-3 business days. At times these items may take longer to ship. By contacting us via our contact form here we can give you an estimate on shipment.
No orders are shipped on weekends or holidays. If we are experiencing a high volume of orders, shipments may be delayed by a few days. If there will be a significant delay in shipment of your order, we will contact you via email or telephone. Please allow additional days in transit for delivery. Please make sure when submitting an order that your address is correct.
Free ShippingFree shipping is available within the lower 48 states for some products. Simply select the free shipping option during checkout, if it's available. (This does not apply to large items or items where shipping quotes are required (ie: bumpers, seats, GT Wings, and so on). Individual items with Free Shipping will be shipped by the carrier of our choice to a single address within the continental United States. This offer excludes shipments going to Alaska, Hawaii, Military Boxes, and items too large to ship via a standard carrier.
Duties and CustomsWhen shipping internationally Complex Seven is not responsible for Duties and customs fee's. These fees must be paid directly to the courier as we do not impose them.
Address RestrictionsThe billing and shipping address must be the same. If it is not we will call or email to verify the inconsistent addresses. This will put a hold on processing your order. If no response from either communication channels, your order will be cancelled and refunded in full.
We don’t ship to PO Boxes.
ReturnsAll returns are subject to re-stocking fee up to 20%. The restocking fee covers the cost of our order processing and restocking process. Items you wish to return MUST be approved prior to your return. Please click here to start the return process. All return inquiries must be sent to us within 30 days of receiving your order. Approved returns MUST be sent back to us within 15 days of receiving your return approval. Returned items must be in brand new condition or, unused condition. Shipping, handling, and transaction fees are non-refundable.
No returns, cancellations, or refunds are allowed on special order items. Once items have been returned to us, and the condition has been inspected and approved, a refund will be issued. Approved refunds are issued within 2-3 business days. Also note that each bank process returns differently, so it might not appear in your account immediately. Exchanges
Please click here to initiate an exchange. Exchanges are subject to second shipping charges unless there was a mistake made on the order. If a mistake was made by Complex Seven Industries, we will provide a return shipping label for you to use to make the exchange as seamless as possible.
