Sorry couldnt find this anywhere - are the arp headstuds reuasble, or are they TTY and can only be used once? A tc im working on had some valve damage and i had to pull the head - guy is using arp head studs just wondering if i need to advise him to replace them or not. Thanks!

 

you can reuse them.

 

Sweet thats what i was thinking

 

yea all arp head studs(to my knowledge) are reusable.

 

Just like OEM head bolts/studs they loose their strength after the initial torque. All head bolts/studs should be replaced and not reused. What do they cost $60-80 dollars is better than paying hundreds later to redo it right. We had a company come to our work and do a demonstration of how bolts loose their strength after torquing them down. I don't remember exact numbers but this is close 1st torque 2100 psi, 2nd 1600, and 3rd 1100 psi this was done on grade 8 bolts however studs are the same either the stud or the nut looses just like bolts do.

 

That is correct. All engine fasteners, i.e. head stud/bolt, main stud/bolt, rod bolts, etc. SHOULD NOT be reused once they have been used on a running motor.

MrC

 

I just spoke with Kammy in the technical department at ARP and she states ARP head studs are reuseable.

 

I talked with them before and they seemed really hesitant on it. I would not reuse them it is easy insurance to pay $60-80 dollars and not have to worry about it.

 

I suppose if that is what you would like to do. However in the spirit of putting factual information out there to the community and not speculation that is why I called and spoke to someone from ARP directly and listed her name for reference.

I personally have been reusing ARP head studs for years in many different applications. I might consider replacing them on an engine that is running 35+psi on a regular basis. Or just go to L19 or a really nice A1 headstud.

Not trying to ____ in your corn flakes I'm just trying to help this young community stay informed.

 

Why take a chance on a few thousand dollar motor when you can a have piece of mind using new fasteners that cost a few hundred. There's other less critical things that you can cut corners on to save money, but a built motor pushing 3-4 times the factory hp is not one of them.

MrC

 

It is a fact that all bolts/studs/nuts loose strength with each time they are tightened. If I had access to the same demonstration I have seen using the exact same torque wrench on the same setting each time it was torqued to similar torque of head bolts it lost a significant amount of strength I would show you. ARP might loose as much but it will still loose its strength.


BTW Mr C I wish I could say my motor is only a few thousand dollars it will be a very expensive engine for me and pocket change for people with sponsors.

 

Opinions aside. The fact is they are reuseable. I have recorded a set of head studs stretch over 30 cycles. Less than two tenths (machinist speak for .0002") of stretch. If torqued with the lube and to the spec listed for the particular stud you should not have much of a problem.

This is on a 650whp 4g63. Studs are studs. It's like anything proper use, lube and torque.

If you want to spend the money on new headstuds each time you can, however it is not necessary. That is a fact.

 

You are absolutely correct it will torque to spec but the holding strength is lost even with the exact same torque. This company used a special tool to measure pressure of the material the bolt tightened down. 1st torque it has 2100 psi of clamping pressure and the 2nd torque it went to 1600 psi.

 

If it isn't stretching then it shouldn't lose it's ability to hold. A stud exerts it's clamping force differently than a bolt. Bolts will stretch easier than a stud. I don't know the complete amount of torque difference but this would be the reason we use studs and not bolts.

 

Yes they do and between the stud and nut is where the stretching occurs, the stud may show very slight stretch but the nut will have the majority of it.

I am sorry it is a proving fact that not every tech that works for a certain company knows their product inside and out. This would be a key selling factor to list on the site if in fact they are safe to reuse and provide the adequate pressure needed to seal after they have been previously torqued. The website contains no information.

 

what are the torque specs for the ARP headstuds when installing the head ?

 

i installed my head today and torqued them to 20ft lbs, 40ft lbs, then 60 ft lbs 3 times.

 

Torque on the headstuds from arp using arp lube is 80 ft lbs