S.S. exhaust studs

[feelyx]

I found some 3/8" SS studs and silver plated lock nuts that are good to 400 + some odd degrees F. Tried mounting them on a spare head, and this job isn't for the squimish Had to drill the "stud hole" out with an "O" bit and drill the header with a 25/64" bit. check it out in the pics

Tim in Sac

[Mukilteo911]

now that is one of tyhe most needed things I have ever seen. I have wondered why SS studs were not used in the first place.

[silverc4s]

What do you mean by "good to" 400 deg F? They will get a LOT hotter than that, right? What happens above 400 degrees? Do your nuts fall off? hmmmmmm....;-)

[mb911]

CHT's should not be getting beyond that point. You may be thinking of exhaust gas temps which exceed 1400 degrees more like 1500-1600. This is typically at the flame tip and the flame tip is about a couple of inches or so from where the pipe meets the head. SS depending on which alloy is good to 600-1000 degrees without any major deformation. This is an awesome idea. Up until now I always trusted anti seize in this area.

Ben

[silverc4s]

Ben,
While you may be correct regarding "cylinder head temperature" the exhaust flange is NOT where that measurement is taken, and is likely the hottest place on the head. (Possible exception to the ex valve & guide)...;-)

[mb911]

Bill,

You may be right. Just don't really think there is a problem with those studs at 400 degrees. I'm sure just a disclaimer from manufacturer. Well its been fun chatting now off to tuck in the cars.

Ben

77 911s 3.0
75 914-6 2.7 (sorry I think this one is more fun)

[RoninLB]

Originally posted by mb911

and the flame tip is about a couple of inches or so from where the pipe meets the head.

Hey Ben.. great info for me..

so this at max rpm?
how long do you figure it would be at 4k rpm? .. just an educated guess is cool, LOL.............Ron

[RoninLB]

Originally posted by silverc4s

[B What happens above 400 degrees? Do your nuts fall off? hmmmmmm....;-) [/B]

hey guy.. you made an educated question.

SS can be a PIA.. I've done SS successfully for a very long time.. but I figured out a technique for fastening them around engine and exhaust heat.. or else the routine would be "nuts fall off"

[silverc4s]

Yeah, Ron. It may have sounded like I was being a wiseacre, but I really want to know if there are limitations to using SS hardware in this area....;-<

[Oldporsche]

I've always had mixed feelings about this product.

Stainless can be a PIA. I thought that the next time I would get into this area on my own car, I would use brass nuts or copper. BTW, stainless WILL hold rust. I guess that these studs were offered with stainless nuts?

Good luck,
David Duffield

[RoninLB]

Originally posted by old_porsche

I would use brass nuts or copper. BTW, stainless WILL hold rust.

copper is great with the "rust".. it's a little soft though for my act.. maybe you could eyeball silicone bronze.. it's much harder than copper, but doesn't look as "beautiful" as copper.. BUT, it's a class act and easily recognized by someone who knows what their looking at.. and it's easily, and efficently used on marine exhaust systems/sometimes..

I will bring a magnet to the store to shop for SS.. if it takes a magnet, then NG.. if it "hardly" takes a magnet then OK.. around here Home Depot has the best prices on SS.. don't know where they're getting it? but many marine wrenches are getting it there. Metric SS will take some time to locate.. I use it on engine sheet metal, exhaust studs, etc... but not on intake runners to heads. you gotta have a technique for the "heat" applications..it would be inefficent for a shop to use SS/generally for the "heat" areas.. but a weekend wrench can do it because of the early stage re- torqueing.
So, IMO, SS is not the proper nuts for exhaust from an engineering point of view.. but I'm not an engineer..........Ron

[RoninLB]

Originally posted by silverc4s

. It may have sounded like I was being a

dealing with nuts is a package deal.. like dealing with humans, LOL..or is it that humans and nuts are the package deal/ not sure, LOL.. sometimes my nuts aren't torqued properly either, LOL.. somehow not being properly socially correct allows honesty to blast thru.............Ron

[feelyx]

Actually, I am not to worried about "my nuts falling off" These are for aircraft exhaust and are very high quality. Also they are not ss nuts, they are silver plated for corrosion resistance, but not corrosion proof. So they may or my not rust. I am doing this because I am doing a turbo engine, and don't want to be plagued with broken exh studs from continually removing my exh to test different designs. My big concern is if what happens "when one does break" and trying to drill it out.

Tim in Sac

[ChrisBennet]

I thought about using stainless fasteners on exhaust a few years ago and someone (Juha) advised me against it. Some of you may remember Juha Vane from the old 911 lists.

My question to him:
"I am trying to think of ways to make swapping the exhaust system easier in the future. I was thinking of using stainless hardware for the the muffler joints themselves. Maybe some super-duper anti-seize for the barrel nuts holding the headers on. Suggestions?"

Juha's response:
"I would be very careful with stainless fasteners, stainless, or there is a myriad of them, but the regular stainless bolts are 316. They gall easily, the threads just weld together. If You use copper or aluminium antisize paste on stainless you create electrical corrosion. Use zink, the white stuff. I have used on my exhaust bolts copper antisieze and all bolts opened up easily. Some cars use copper plated nuts in exhaust manifold, Audi for example. This would be good, but the barrel = nuts are steel."

(I use the "copper" exhaust nuts.)
-Chris

[RoninLB]

Originally posted by ChrisBennet

but the regular stainless bolts are 316. They gall easily, the threads just weld together. If You use copper or aluminium antisize paste on stainless you create electrical corrosion. Use zink, the white stuff.

I never paid attention to the SS numbers because I grew up with the magnet act when checking out stainless.. I have never had threads weld together.. and the routine silver anti-seize has always been used.. and if they had to be fully loosened and tightened.. they seem to be good for 2X.. after 2X, for some reason, they are more likely to loosen. so I will re-check them an extra heat cycle or two.. I just treated new SSI to new SS head nuts and muffler flange nuts and bolts.. and my world is routine 60%-90% salt air humidity.. not trying to argue a position on SS.. I'm only stating my experience w/SS as exhaust fastners......Ron

[mb911]

Roninlb

Flame tip typically varies slitly. Most application (engines in general ) use EGT probes about 1" to 3 1/2 inches away from gasket area. If you look at the avaition end of it probably no more then 2". These are where the flame tips stay as these are the hottest points. With all engines and many variables these things change.

As far as the subject here is my trick and never had a problem. I use stock steel studs and then use all stainless nuts and washers. I also use anti sieze and things seam to work fine. If your statement is true about these bolts being aircraft grade they could be 304, 308, 316, etc. They could even be 4 series but very unlikely ( by the way 4 series is magnetic and 3 series can become magnetic through cold working) As for the answer using copper nuts. They are not copper all the way through but rather coated. That has caused to be a problem as well.

Ben

77 911 3.0
75 914-6 2.7

[HawgRyder]

In the normal day at work...I use 50 - 100 stainless fasteners.
Caveat here....stainless is NOT strong!
Stainless (18-8) is used everywhere in the movie industry...because you absolutely cannot have them rust and seize....it takes too much time to break down a set and move if it does.
Yes...anti-seize with plastic type lock nuts...every time.
For the motor...I have used stainless for the exhaust....but with brass nuts and lock washers.
This setup does not rust or seize....and is long lasting.
If you use stainless for the exhaust studs...locktite them in or they will back out every time.
Bob

[Mukilteo911]

as far as anti sease compounds go, what about the stuff they use on oxygen sensor threads. I just put calmini headers on my trooper and they used some sort of high temp lube on the threads of it

[RoninLB]

I use the nickel anti-seize on exhaust/lately, and Graphite-50 anti-seize on spark plugs.. and the routine silver on most else.. ..........Ron

[Wil Ferch]

I'm surpised no one has come up with this:
- stainless steel studs with SILICON BRONZE nuts.

Si/Br is *much* stronger than brass or copper and will not gall against SS. I'm using this combo on the rest of my exhaust system.
---Wil Ferch