ARP Head Stud Kits

These studs are rated at 190,000 PSI (consider that Grade 8 is less than 150,000 PSI).
Included washers are hardened, and the 12 point type nuts are of the aircraft type.
The following head stud kits include rocker studs, nuts + washers: HSA9, HSA11, HSA11-B, HSB42
Always wash and inspect the product upon opening.
The oily coating on the parts is a rust preventive, and does not therefore have any lubricating properties.
30 cwt. engine oil, or the recommended ARP lube, part number L99 should always be used, and the different torque specifications for each type of lube followed.
The tension obtained in the fastener (which is what we need) is affected by how well the lubricant being used is coated evenly on the threads.

When using oil, and especially when using the ARP low friction lube, it is highly recommended that the following technique is followed:
- Coat the fastener with the lubricant, and especially with the lube, try and rub it into the threads as evenly as possible.
- Screw the nut down and pull up snugly with a wrench (spanner), repeat this three times.
- On the third go torque to the recommended torque setting.

All of the above might sound a little odd, but many carefully controlled tests have shown that this method distributes the lube evenly between the friction surfaces, so increasing the tension each time for a given torque.
The difference in tensile load between step #1 and step #3 can easily be well over 1000 pounds on a 3/8" stud or bolt… very significant!
Always run a tap down each threaded hole prior to installing the studs.
Use a bottom tap (called a plug or #3 tap in England).
Where possible we recommend using a 60 degree counter sink into the top of each stud hole. This will help stop the top threads being pulled up above the surface.
We don’t recommend using Loctite type compounds on studs or bolts, but if you feel you want to, then be sure to complete the job, including final torqueing before the compound 'sets up'.
Studs should not be screwed into the block very tightly, only about 4 ft lbs is all that is required (not much more than hand tight).
The torque figures we recommend will give a preload equal to 75% of the yield strength of the fastener.

If you have any questions, please contact us BEFORE proceeding.
ARP is a quality product, and like many other things in life, sometimes when you get into it a bit, you might find there is a little more involved than just "screwing it together"!