We have a car here we are putting back together. It has been through a few too many shops and was a complete mess.

The new engine is going back together and we were torqueing the head studs, the same one the car came in here with. Luckily after doing a few thousand of these builds you get a feel for things. When something didn't feel right the stud was pulled out.

Below is a picture of the stud. We aren't sure why this happened (other than it was obviously tightened to tight past it's tensil strength). It is odd as we've re-used hundreds of ARP fasteners without a problem. My guess is someone in the past over torqued them and this was the result.



Be careful.

 

good info dave.. for the price of what standard ARP studs cost we require they buy new always and they can have back the old.. That is if we didnt do the original install and know how many times they have been on and off.. Just our policy..

 

I guess somebody needs to get off the roids and look up torque specs. That is not easy to do.

 

I'm gonna go out on a limb and say those were probably installed previously with an impact and then torqued down... Don't ask me how I know...

 

what retard would even think about attempting that

 

Im thinking with impact as well, but i dont see messed up threads, weird.

 

I'm surprised the Tap didn't strip.

 

had to be a suepa impact wrench

 

...

 

interesting. I wonder why it just didnt break? Did not know that studs could do that.

 

what do you generally tq these to? Stick with the arp recc of 75 or..?

 

Any chance it's a knock-off or counterfeit?

 

The 75 ft lb ARP spec is not tight enough. The stud is not that strong and the diameter is "small". They can be torqued to about 90 ft lbs with no problem. Anymore and they stretch. In this case I am guessing someone attempted 100+ on them and that is not possible.

I suppose it could be a counterfit stud but it was probably just installed wrong before we got the car.

 

DAve, do you know off hand if the cosworth stud ( which i am sure is made by arp ) is the same as the ARP standard stud or is it a bit stronger?? I know the L19's are the mack daddy stud but i did my cosworth studs to 100ft lb and they felt real good going in.. No issues of them spinning etc..

 

Cosworth has had a couple different part numbers for their head studs

The first ones were like the std ARP you see in the picture.

The new ones are L19(have not confirmed if ARP is the manufacturer or not)

The new part number MSRP out at $299 Where the old one was 187 or something like that.

Ben