Head Bolts

All Pro Series Head Bolts are cold-forged to ensure molecular integrity, heat-treated prior to thread rolling and machining, and are rated nominally at 190,000 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 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.

Come here looking for ARP Head Studs?

• AMC
• Buick
• Chevrolet Big Block
• Chevrolet Small Block
• Chevrolet V6
• Chrysler Big Block
• Chrysler Small Block
• Ford Big Block
• Ford Small Block
• Harley Motorcycle
• Holden
• Mini Cooper
• Oldsmobile
• Pontiac
• Toyota

HEAD STUDS vs. BOLTS...A TECHNICAL DISCUSSION

ARP's factory Tech Representatives are often asked which is better, cylinder head studs or bolts. The answer, invariably, depends on the installation. 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. Alamo Motorsports offers the complete line of ARP Head Studs in addition to ARP Head bolts.

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.