ARP Head Studs
 

I am right in the middle of building a 3.ol 911 engine and bought ARP studs to replace the originals. Wayne's book states that the studs should be out 135mm with the originals. The ARP bottomed out at 135mm but the decorative rounded top goes to 140mm. Can somebody tell me if this is correct? Boy, I'd appreciate it if somebody who has done this could answer me back quickly. I'm bouncing around waiting to move forward.

Thanks. Jimmyhttp://www.pelicanparts.com/support/...s/a_frusty.gif

with the arp studs you don't have to worry about the height. using the barrel nuts the original studs can't be too high or you run out of space in the barrel nut to torque them. with the arp you have 12pt nuts to torque down. don't know if i explained that very well but the height will be ok

jjemg,

I just finished using the ARP head studs. The height is correct when measuring to the top of the constant cross section, just before the rounded top starts.

Rex

Michael, you did well. Jimmy, the key is the barrel nuts aren't open on top but the ARP nuts are, so you can't "bottom out" the ARP nuts and get a false torque reading which makes the length OK.

The ARP studs have only a small section that is threaded. I was concerned that the nut wouldn't end up torqued onto a threaded portion (too high or too low on the stud), so I figured out what the height should be to get the nut right in the middle of the threaded part. Measured to the point where the rounded top starts was correct.

Rex

Thanks guys for the quick response. For the huge expense of these studs, I don't want to screw it up! You answered my questions. Okay....back to work!

Jimmy

Actually, the factory barrel nuts are open at the top. If the stud is too long, as it enters the upper area of the nut it pushes the Allen tool end out. A guy can compensate for this if it is not way off by adding washers (if he doesn't worry about not having enough thread engagement in the case, that is.

Using a nut with a socket avoids this problem. I have taken to using flange nuts for stock threaded studs, and these seem to work well. The advantage a flange nut seems to have over a barrel nut (leaving aside compensation for some minor slip up in stud installation height) is that its smaller profile is a bit less of an obstruction to the cooling air flow. It also weighs less, though that isn't going to add up to a whole lot.

Are ARP studs back in stock?

Walt Fricke

Walt,

Appreciate you getting back with me on this. It appears after inspection that the correct stud length is paramount to using the washers and nuts provided. Put the heads on and they seem to be working well. I'm just trying to be thorough and I'm probably a bit overcautious because I don't have the money to go "oops time to do it again". I really appreciate you getting back to me.

Jimmy