ARP HEAD STUD FIXING KITS

Material spec
These studs are machined from ARP2000, an alloy steel with a tensile strength of 220,000 PSI. ARP2000 is used widely in motorsport applications as an upgrade from 8740 chrome moly in both steel and aluminium rods. Stress corrosion and hydrogen embrittlement are typically not a problem, providing care is taken during installation.

Lifetime
As long as the fasteners have been installed and torqued correctly, and show no visible signs of damage, they can be re-used. If they show any signs of thread galling or corrosion, they should be replaced. 

Stud torque settings
Cylinder head studs are installed only hand tight. The hex in the end of the stud is to ease installation, not to apply torque. However, it is extremely important to ensure that the studs are fully bottomed out in the hole in the block and not hung up on damaged or corroded threads in the block preventing the stud from being fully seated. This is often indicated when the stud threads extend past the deck surface.

Stud nut torque settings
We recommend using the supplied ARP Ultra-Torque lube to ensure an even, accurate clamp load and to prevent thread galling. The lube should be used under the head of the bolt or the bearing surface of the nut and on the threads, unless a thread sealer is used. Torque the head stud nuts to 45-50lb.ft and the rocker pedestal nuts to 25lb.ft.

Fitment order 
After test fitting the studs in the block, it is generally easier to remove the studs, put the head gasket and head on the block and install the studs. This will reduce the possibility of damaging the upper threads of the stud and scraping the cylinder mounting holes.

11th stud sealant 
We always recommend installing the 11th head stud at the water pump end of the engine with a coating of silicone sealer, as this protrudes into the water jacket. Failure to do this may result in a coolant leak.

Washer orientation 
The chamfered side of the washer goes up, towards the head of the bolt. The chamfer is there to create clearance for the radius between the bolt shank and the bolt head.

Rust resistance
These will corrode over time if not protected from the elements. The black oxide process is a short-term rust preventative only, so an application of oil to the part will increase corrosion resistance.