Stud size for exhause manifold

[Bruce Allert]

Found a stud missing from the exhaust manifold on the right side. Does anyone know the size of the stud? I've been hearing what I think is an exhaust leak. The Pelican spec drawings of the cylinder & head show a 10mm nut. Would this be it?I hope the stud just worked its way out and didn't break
bruce

[roadtrp204]

The original stud thread size is 8mm X 1.25. I am not sure on the length. The original nuts are shouldered and have a thread insert in them like a helicoil. I was missing a coulple and bought 8 911 allen nuts for the heat exchanges. I found them much easier to tighten than the original nuts because the socket doesn't get stuck between the nut and exhaust pipe.


http://www.pelicanparts.com/catalog/shopcart/911E/POR_911E_exhaus_pg2.htm#item12

[Tom Perso]

Man, those nuts are way cool! I should get a set, I have had some problems getting a socket in to tighten my exhaust nuts.

For the stud, most are 8x1.25, on my 1.8 heads, they are 8x1.25 on the exhaust end and on the head end is 9x1.25.

Try finding THAT stepped stud.

Actually, your VW dealer has them in stock, just do a search on a 74 or 75 VW van, and look at the pics they pull up. They will have two choices for exhaust studs, the standard 8x8 ones or the 8x9 ones.

Warning, they are not cheap.

Later,
Tom

[jamcleod]

8mmx53mm but i found 8x55 at the local auto parts store and used them. the 911 nut looks like a great idea, i agree, the hex head nut is really hard to get to.

[Bruce Allert]

Found some metric automotive studs at the local ACE hardware store. Multiple lengths & sizes! Even found the 8mm x 53. Roadtrp mentioned a shouldered nut w/ helicoil insert. Is this really necessary or would a standard automotive metric nut work? ALSO... is there a trick to putting the stud in or can it be installed with some red locktite?
bruce

[roadtrp204]

I am assuming you have the heat exchange off. Put two nuts on the stud and run it in until snug. Not sure if loctite would be of any benefit, I believe that part of the head runs above the temp required to remove red loctite.

When I lost a couple of the original nuts I used some exhaust nuts from a VW type I kit (look just like the ones Pelican shows for type IV replacements).

They siezed on all the studs of one head and broke all the studs when I tried to remove them. I probably overheated the head and caused the problem but in any case I will never use that type of nut again. Next I tried regular metric nuts and washers, I had to grind a flat spot in the washer so it would fit (washers have a larger diameter than the OE shoulder nut). The regular nuts seem to always come loose, maybe a thick washer (like a VW 8mm head washer) would solve that problem.

NOTE
When using the 911 allen barrel nut, the stud cannot be to long. If it is it will push the allen wrench out of the nut as you tighten it.

[Bruce Allert]

Hey, thanks there "RT". I got a couple lengths. Hopefully one of them will do the trick.
I assume that the studs to use are completely threaded, from one end to the other. I came across some that had unthreaded centers. I'll try what I have.
thanks
bruce