Stainless steel exhaust port studs

[JFairman]

I have 12 new stainless steel studs that were part of a PMO carburater heat insulator kit.
They are the the right size and length to use as exhaust port studs with thick flange B&B headers on a 911 turbo.

I'd like to use them as exhaust port studs if they will last and not break or gall because they won't rust but I've heard some people say do not use them for whatever reason and others say yes go ahead and use them.

I know ARP makes nice stainless steel exhaust port studs and maybe they are a different alloy that's better with the heat of exhaust and will hold up better than these PMO studs. They sure cost alot more so it makes me think they are a better stainless steel alloy for this application.

I would install them in the heads with some red loctite on the threads and use new copper coated exhaust nuts on them. I would coat the stud and nut threads with permatex nickle anti-seize thats good up to 2400 degrees.
If I needed to remove them from the heads I would use MAP gas or acetylene and oxygen torch to carefully heat up the head around the stud and soften the loctite before trying to unscrew it with double nuts or a stud extractor.

I'd like to hear opinions from the experienced people here on using these PMO stainless steel intake studs as exhaust port studs on a 911 turbo.
I also have some used plain steel studs I've collected over the years that are also the right length and I could use those instead. They were probably intake studs on old BMW's I've had and I don't know if they would hold up long as exhaust studs either.

Thanks in advance for any helpful advice.
Jim

[tctnd]

If you use them (I would), do not under any circumstance use stainless nuts; they will gall in a heartbeat. Plain steel nuts with a touch of anti-sieze and you'll be fine.
regards,
Phil

[HawgRyder]

I prefer brass nuts on stainless studs....good for decades....no galling....seal nicely...not too hard to remove when necessary.
Bob

[JFairman]

Thanks for the thumbs up on them. They're installed now with red loctite.

[Lapkritis]

I have the arp stainless exhaust studs on another make high $$$ European engine build. The bits are beautiful...

[RedCoupe]

The comments in this thread about galling are well founded. However, I recently researched thread galling and found that Fastenal has a good article about it on their website. Fastenal says that different stainless alloys can have sufficiently different properties that they can be okay to use together without galling. For example if the stud is a 400 series alloy and the nut is a 316 alloy, it should cause thread galling like a nut and stud of the same alloy. Who knew?

[RedCoupe]

Okay, what I really meant to say was that a 400 series stainless nut or stud could work okay with a 316 series nut or stud without galling. At least according to Fastenal.

[JFairman]

I've seen pics of the ARP stainless exhaust port studs and they are really nice. I remember the little allen head socket in the outer end.

I got these PMO stainless studs around 6 years ago with plastic insulator blocks with 12 gaskets that fit some aluminum CIS injector blocks I have like they were made for them. The PMO kit was around $50.

I've wanted to use the studs as exhaust port studs and now they're finally in. I just put in new 3.3 turbo pistons and cylinders, had the rods resized, and did a bunch of other stuff to freshen it up. Hopefully it'll be running in around a week.

Here's a pic of the bottom after I put the exhaust studs in earlier today. I'm doing all this with the motor in the car.

[Lapkritis]

Originally Posted by JFairman

I've seen pics of the ARP stainless exhaust port studs and they are really nice. I remember the little allen head

Mmm... bout $160 if you know where to look:

[safe]

Heads are probably hot enough to keep moisture away, but I have seen stainless screws in aluminum wheels eat away the aluminum.
Either way, I would use plenty of loctite to isolate the head from the stainless bolts.

[0396]

Originally Posted by Lapkritis

Mmm... bout $160 if you know where to look:

Ok..Where's the source? Thanks

[911pcars]

Originally Posted by safe

Heads are probably hot enough to keep moisture away, but I have seen stainless screws in aluminum wheels eat away the aluminum.
Either way, I would use plenty of loctite to isolate the head from the stainless bolts.

Loctite is usually synonymous with threadlocking compounds. They also sell, among other products, gasket sealants and industrial glues.

Did you mean using anti-seize between the dissimilar metals or threadlocker?

Here's a helpful guide to using dissimilar materials:
Guideline for Selection of Fasteners based on Galvanic Action
18-8 Stainless steel, 304, 316 Stainless Steel Corrosion

..... and an engineer's suggestion for using one over the other, albeit for another mode of transportation:
Hack Racer: Part 2 - The arguement for using threadlocker vs Antisieze in almost all areas

While threadlocker seems acceptable to prevent galvanic reaction in certain situations, I'd choose a product that won't paint you into a corner if/when future removal is needed, and I wouldn't rely on a small internal hex to extract an exhaust stud after some years in service.

Sherwood

[safe]

Originally Posted by 911pcars

Loctite is usually synonymous with threadlocking compounds. They also sell, among other products, gasket sealants and industrial glues.

Did you mean using anti-seize between the dissimilar metals or threadlocker?

Here's a helpful guide to using dissimilar materials:
Guideline for Selection of Fasteners based on Galvanic Action
18-8 Stainless steel, 304, 316 Stainless Steel Corrosion

..... and an engineer's suggestion for using one over the other, albeit for another mode of transportation:
Hack Racer: Part 2 - The arguement for using threadlocker vs Antisieze in almost all areas

While threadlocker seems acceptable to prevent galvanic reaction in certain situations, I'd choose a product that won't paint you into a corner if/when future removal is needed, and I wouldn't rely on a small internal hex to extract an exhaust stud after some years in service.

Sherwood

Sorry, I was a bit unclear.
As you say, I was suggesting using threadlocker as a barrier against galvanic reaction.

[1968DT]

Anyone know which SS ARP p/n I would use on a 2.0L exhaust (ssi)? Intake (webers)?

Thanks.

[911pcars]

Originally Posted by 1968DT

Anyone know which SS ARP p/n I would use on a 2.0L exhaust (ssi)? Intake (webers)?

Thanks.

Not sure the advantage of ARP SS studs over other manufacturers. Here's one source for individual prices:
McMaster-Carr

[Lapkritis]

Originally Posted by 911pcars

Not sure the advantage of ARP SS studs over other manufacturers. Here's one source for individual prices:
McMaster-Carr

The handy Allen head is nice and the warranty/washers/nuts.

http://m.summitracing.com/parts/arp-400-8002

There are many lengths available so choose based upon the thickness of flange you're fastening. Most available in 4 packs so order 3 total sets to get 12.

[larrym]

galling ?? - only an issue if you are planning to R&R the nuts 17 times in the next 5000 miles

?

i used 'em on MY 3.2
.

[porschetub]

wouldn't use them cause they look too nice no not really because the long term effect being screwed into alloy worries me,and there is the old stainless issue of "work hardening" ,did Porsche ever use them? just my 2 cents

[Lapkritis]

Originally Posted by porschetub

wouldn't use them cause they look too nice no not really because the long term effect being screwed into alloy worries me,and there is the old stainless issue of "work hardening" ,did Porsche ever use them? just my 2 cents

Cost; Profit; technology

If you look at materials selections for vehicles then it's obvious there is a trade off between quality and cost for virtually every part. The timeless battle between engineers and accountants stares us in the face daily with all manufactured goods. A Porsche is no exception. Stainless fasteners are far more expensive all around. I expect they would have been scoffed at as eating into profits and being unnecessary as they would be overkill for the application on a scale where the multiplicative effect would be measured in millions of dollars.

Secondly, fastener material technology and manufacturing process has advanced tremendously in 50yrs. We have grades of materials at our disposal now that were previously not part of the conversation for the common Joe wrenching at home. We're very fortunate to have these choices.