I've just ordered some shorter exhaust studs for my Duratec V6 and the new exhaust system (for a scary price) and I noticed that the supplier
lists copper exhaust nuts.
My experience must be lacking in this department as I have never used (or noticed) copper nuts before. What is the reason for using copper? Is it to
lessen corrosion? Do I use washers with them?
steel ones will get so hot and basically weld them selves on, use copper grease aswell.,and use spring washers to stop them vibrating loose
Copper ones or will steel do?
I have always used K Nuts in the past - but thinking about it I have never had to remove a manifold fitted like that. I bet the new owner of my old
Nissan S13 is cursing me for using steel nuts on the manifolds and turbo! 
[Edited on 23-11-05 by RazMan]
quote:
Originally posted by RazMan
I have never used (or noticed) copper nuts before. What is the reason for using copper? Is it to lessen corrosion? Do I use washers with them?
quote:
Originally posted by Kowalski
.....as corrode on and can be a pain to shit.
I will definitely put this down as 'the thing I learned today'
Thanks for the input guys - I'm all set to put the exhaust on at the weekend now 
I was sent copper nuts as standard from burton but they wouldn't get the exhaust studs in the block and they were so soft that they couldn't
pull the manifod in tight enough so it kept blowing. Burton said this was the standard and they didn't do steel exhaust nuts.
I asked them if they knew the tread size of the copper? "yes sir"
Do you have regular steel as opposed to exhaust steel nuts of this size? 'Yes sir"
Well send me them then! 'OK sir'
They worked fine.
The "proper" solution is usually Copper Coated K-nuts.
These are flanged nuts which are slightly crimped at the back end to keep tight on their threads, and are copper coated to achieve the anti-seize
properties.
They would be my preference but I can't find any copper coated ones - just standard full nuts. 
I've got bronze nuts (ooer!) from Burtons - they're about 3 times thicker than std nuts to keep the strength up. Seem to work OK.
If I over-tightened them I'd rather strip the nut's thread than wreck the stud.
David
I just did a Google for K Nuts and came across a company in Silverstone who stock 'Silvered' Stainless K Nuts for aircraft exhaust
applications. I gave them a call and they have loads of stock ..... but at £3.45 per nut I think I will revert back to plan A and use the standard
copper nuts!
http://www.tridentracing.co.uk/info/fastas.htm
[Edited on 24-11-05 by RazMan]
I would be very surprised if the copper nuts you refer to are actually solid copper. Ill put money on that they are the copper plated K nuts that Nat
refers to. (Incidentally - ive also heard these referred to as 'bugger nuts'! nice name me thought).
Ive used copper coated on mine. Came with the new studs i fitted when reconning the head. Unfortunately supplied with second hand engine i bought off
PeteBee so i dont know where they can from - i think they were main dealer parts.
I am surprised you say copper - copper is not very strong. I have seen and used brass nuts in the past, muich harder than copper.
You may want to consider stainless steel?
Whichever you use, sbe generaous withthe copper grease when fitting.
Mine are certainly not plated steel - I checked!
DJ
If a nut welds itself to a stud, doesn't that then become a bolt? Surely it would undo just like a bolt would?
It's when it welds itself to the stud, AND seizes in the head that you REALLY get pee'd off! 
DJ
I've used brass nuts to good effect, they pull down well. Ensure you use spring washers in addition to the normal.
Cheers,
Dave
The nuts as supplied by Ford are the copperED variety, crimped at the end as described in an earlier post.
I've got some second hand ones in the garage you can have Mike if you want to pop round. I'm going to use stainless studding and stainless
nuts on the Zetec.
As my feeble memory recalls, the Brass nuts onto manifold studs were for the expansion properties. As I was told brass has a different expansion rate
to steel so does not become loose after numerous hot-cold cycles.
Corrosion would only be a problem if left for a great period of time unused (as in parking up for winter). It is the expansion and contraction of the
manifold that causes the problems, making the steel stud stretch. By having the brass nut as the retainer and being softer it allows the components to
stretch and contract easier without loosening up.
I hope this makes sense!
Terry