Exhaust stud torque?

[PabloX]

Ok, I searched (forum, manuals, etc) and I'm not finding it exactly.

What is the torque for new exhaust studs? I've seen vague mentions of 18ft/lbs which seems about right but I'd like to be sure. I also want to use anti-seize if that matters.

I took the family to the local ice cream stand and everybody else finally has their weekend cars out, and it's making me a bit desperate.

Thanks.

[JAR0023]

18 ft-lbs per Bentley manual. -J

[pete3799]

Yup.....18ft.lbs.

[whiz05403]

Take that with a grain of salt.

Crank it too much and bye bye exhaust stud. (ask me how I know)

[PabloX]

Just to follow up on this, I was talking about putting the studs into the heads, not the torque for the nuts that hold on the manifold.

Anyway, I think I agree with whiz05403. I put the new studs in with a torque wrench and the double nut method. The nuts would end up spinning before I was able to get 18ft lbs. When I took the heat exchangers off, most of the studs came out but 3 or 4 were left in. So, on those where the double nuts started to turn, I measured the exposed length and it was very close to the originals. So, I'm stopping there.

I'll put the nuts on at 18ft lbs.

[cabmandone]

Originally Posted by PabloX

Just to follow up on this, I was talking about putting the studs into the heads, not the torque for the nuts that hold on the manifold.

Anyway, I think I agree with whiz05403. I put the new studs in with a torque wrench and the double nut method. The nuts would end up spinning before I was able to get 18ft lbs. When I took the heat exchangers off, most of the studs came out but 3 or 4 were left in. So, on those where the double nuts started to turn, I measured the exposed length and it was very close to the originals. So, I'm stopping there.

I'll put the nuts on at 18ft lbs.

FWIW, I was told and also found in other threads to use Copper anti seize on the exhaust nuts when you put those on.

[PabloX]

Originally Posted by cabmando

FWIW, I was told and also found in other threads to use Copper anti seize on the exhaust nuts when you put those on.

Thanks. Yes, I was definitely going to do that. Also, because of the anti-seize, I was going to go a bit lower on the torque for the nuts, like 15 or 16.

[irobertson]

I don't think there is a torque spec for installing the studs. I used the Snap-On stud tool which is nice because it covers a large number of threads and holds really well. I just put mine in until I could feel the shoulder tighten up against the thread in the head, then gave them another 1/2 turn. Beyond that, I would say you would just be damaging the upper threads in the case or heads.
You also want to be careful not to bottom them out in the hole because of the different coefficients of expansion of the two metals. There should be a little air gap at the bottom. When I drilled out my broken ones, I could feel the drill come out the bottom of the stud because of the space (about 2mm) under the stud.

[PabloX]

Originally Posted by irobertson

I don't think there is a torque spec for installing the studs. I used the Snap-On stud tool which is nice because it covers a large number of threads and holds really well. I just put mine in until I could feel the shoulder tighten up against the thread in the head, then gave them another 1/2 turn. Beyond that, I would say you would just be damaging the upper threads in the case or heads.
You also want to be careful not to bottom them out in the hole because of the different coefficients of expansion of the two metals. There should be a little air gap at the bottom. When I drilled out my broken ones, I could feel the drill come out the bottom of the stud because of the space (about 2mm) under the stud.

Thanks, that's a very good point.

Do you think it makes sense to match the exposed length to the originals?