Intake/Exhaust studs

[millarg]

Aside from possible differences in length, are there any other differences between intake and exhaust studs?

Exhaust studs seem to cost more (about $1 more each than intake), is there any reason to or not to use exhaust studs when replacing the intake manifold.

Also, I have read that exhaust barrel nuts are suggested for use on the intake manifold as there tends to be limited access, is this correct?

With reagrd to removal of existing studs, 4 intake studs came out of the head when I removed the 3.0 intake manifold, I have been spraying the remaining 8 over thelast few days with PB Blaster and tapping with a wooden mallet, how is it suggested that I remove these - vice grips?

Also is it recommended to use locktight when installing the new studs?

Finally, I'm planning on putting a 3.2 intake on a 3.0 78SC, anyone know the recommended torque for the intake bolts and is the a recommended torque pattern?

Many thanks in advance,

[JJ 911SC]

25 Nm (18 ft-lb). As for the pattern, the left side is independent of the right side. So do one bank at the time evenly.

For the Intake nylock are fine.

The problem with barrel nuts is if your stud is protruding too hight you will not be able to thigh it down as the stud will push your tool out.

For the Exhaust one, copper lock nut Porsche 911 & Carrera Exhaust Pipes - Page 4 are fine for the same reason. When I took the barrel nut off my exhaust some of them had 5 washers so they could be tight down.

[cstreit]

There are differences on some models in the metalurgy, but i dont have a list. If the peice is different, so is the metal. 993 motorsports studs make a great replacement.

[bullethole]

Try heating the block around the studs... i believe that they are installed with red loctite and that needs heat to allow the stud to remove. I would also suggest using a collet tool to remove the stud, the double bolt trick does not work well in all cases. If your threads are buggered, be sure to use timeserts, not helicoils

[Walt Fricke]

Why do you want to remove studs which didn't back out on their own?

If it is because your new intake system has thicker (or thinner) flanges or plastic heat shielding spacers, fine. Or if threads are buggered and so on. Otherwise, I don't see an issue with reusing these.

I confess I have never torqued these, and have never had a problem as a result. The intakes often won't allow use of a torque wrench without taking special measures any way, and if you can even get a crow foot on them you then have to calculate how much less wrench torque to use to end up with the desired nut torque.

It is helpful to use 12mm wrench size 8mm nuts - more clearance for the wrench. And nuts rather than barrel nuts avoids problems with stud length, which can be especially nasty with exhaust systems.

And I have benefitted with some motors by using a barrel nut for one or two especially hard to wrench nuts - the rearmost inside ones, where the alternator/fan covering is most in the way of a wrench. You just have to make sure the stud doesn't stick out too far, or resolve that with a stack of washers.

[bullethole]

i think he;'s doing the same thing as i am.. going to a 3.2 intake. the spacers between the head and the manifold require a longer stud than the stock 3.2 ones. hence the replacement of all 12 studs.

[millarg]

Many thanks for the tips guys, I used the two nut technique which worked beautifully (I had PB Blasted for about a week first). All intake studs are removed & shroud is free and ready for repainting.
BTW, I am installing the Bitz Racing EFI using a 3.2 intake manifold.