exhaust studs

[otto_kretschmer]

I got under my car to drop the motor and found this



a missing exhaust stud

fortunately it wasn't broken off

I searched on pelican for a m8-1.25 x 55 and didn't find anything that looked like it would work. I found a stud at the local Ace hardware. Its steel and with the right threads and a little shorter than what is on the car now.

This car originally had the thermal reactors and a previous owner got rid of them.

the stud that came with the car has a reduced shank, maybe for better fatigue properties



some of the other studs look kinda iffy, they're rusty and the thread fit is really loose, or they will be after I clean them

I'm considering replacing all the studs with new and I'd like to get some opinions. The studs from Ace seem OK and in an emergency I'm confident they would work fine.

I'm also worried about breaking a stud if I try to remove them. I don't plan on putting huge amounts of miles on the car but I don't want to have any problems on a road trip.

so should I replace all? are the generic studs from ACE ok? are new studs with the reduced shank needed?

thanks

[winders]

Is this for a 2.7L? If yes, look here:

https://www.pelicanparts.com/cgi-bin/ksearch/pel_search_2016.cgi?command=DWsearch&description=99906200602

[otto_kretschmer]

Originally Posted by winders

Is this for a 2.7L? If yes, look here:

https://www.pelicanparts.com/cgi-bin/ksearch/pel_search_2016.cgi?command=DWsearch&description=99906200602

thanks, it is a 2.7

those are too short for the current flange on the headers

I may build a set of equal length headers in the future and then maybe use a thinner flange.

The flange thickness right now is just under 3/4" thick, maybe .70

thread engagement in the head is at least a half inch, add another 3/8 to 1/2 for a nut and washer and maybe .070 for the gasket so I need a stud around 2"

I don't like working in metric. I can when I have to but American standard is much easier for me

[winders]

It's a German car...get used to metric.

https://www.belmetric.com/m8x125-coarse-thread-c-9_71_1840/s8x53eblk-even-stud-black-p-5700.html

[otto_kretschmer]

Originally Posted by winders

It's a German car...get used to metric.

https://www.belmetric.com/m8x125-coarse-thread-c-9_71_1840/s8x53eblk-even-stud-black-p-5700.html

perfect

cool, thanks

that should work

I think its best to replace all the studs now

[winders]

You're welcome!

Bookmark Belmetric....they are a tremendous resource for metric stuff!

[Henry Schmidt]

Because all we do is Porsche air-cooled sixes, we stock every possible nut, bolt and stud you could possibly need.
If we don't have a new one, we'll source a good used one.
Lots of Porsche hardware is unique and difficult to source as new but having disassembled some 60+cores so a bunch of hardware is here.
We also do in-house plating that can make old "junk" look like new.
If a restored part sits on the shelf long enough it might become NLO...lol.

[Henry Schmidt]

Originally Posted by otto_kretschmer

I got under my car to drop the motor and found this



a missing exhaust stud

fortunately it wasn't broken off

I searched on pelican for a m8-1.25 x 55 and didn't find anything that looked like it would work. I found a stud at the local Ace hardware. Its steel and with the right threads and a little shorter than what is on the car now.

This car originally had the thermal reactors and a previous owner got rid of them.

the stud that came without the car has a reduced shank, maybe for better fatigue properties



some of the other studs look kinda iffy, they're rusty and the thread fit is really loose, or they will be after I clean them

I'm considering replacing all the studs with new and I'd like to get some opinions. The studs from Ace seem OK and in an emergency I'm confident they would work fine.

I'm also worried about breaking a stud if I try to remove them. I don't plan on putting huge amounts of miles on the car but I don't want to have any problems on a road trip.

so should I replace all? are the generic studs from ACE ok? are new studs with the reduced shank needed?

thanks

You may find that removing the broken studs will damage the threads in the head or even break off.
Very common on the old thermal reactor engines. There is/was a jig available specifically designed for drilling out the broken stud. If need be, there are also Time-Sert kits that make thread repair fairly painless. 8x1.25

Caveat: Drilling out a broken stud without a jig is courting disaster...don't try it.

[otto_kretschmer]

Originally Posted by Henry Schmidt

You may find that removing the broken studs will damage the threads in the head or even break off.
Very common on the old thermal reactor engines. There is/was a jig available specifically designed for drilling out the broken stud. If need be, there are also Time-Sert kits that make thread repair fairly painless. 8x1.25

Caveat: Drilling out a broken stud with a jig is courting disaster...don't try it.

Henry,

I have a helical thread insert kit but I want to avoid using it if I can. If I replace the studs I want to use new parts. If a stud is going to break I would rather have it break now as I'm pulling the motor out for a long needed service than have it break when I'm a thousand miles from home on a trip.

[356911930]

Hi Henry,

You stated "Caveat: Drilling out a broken stud with a jig is courting disaster...don't try it."

I think you meant to say:

"Caveat: Drilling out a broken stud WITHOUT a jig is courting disaster...don't try it."

Best regards,

Rahl

[Henry Schmidt]

Originally Posted by 356911930

Hi Henry,

You stated "Caveat: Drilling out a broken stud with a jig is courting disaster...don't try it."

I think you meant to say:

"Caveat: Drilling out a broken stud WITHOUT a jig is courting disaster...don't try it."

Best regards,

Rahl

You are correct. I've been known to error upon occasion. I'll correct it.

[mepstein]

Stephen Stompski makes the stud jig. I haven’t looked but it’s probably sold on pelican.

[otto_kretschmer]

Originally Posted by mepstein

Stephen Stompski makes the stud jig. I haven’t looked but it’s probably sold on pelican.

thanks,

not at that point yet, fingers crossed

the missing stud just fell out, didn't strip either

[Flat6pac]

The narrow center stud is typically thermal reactor 77 you needed to rock the reactor to get it seated and the narrow area made the rocking possible.
Bruce

[Walt Fricke]

A good thing about using hex nuts instead of barrel nuts is that having a stud which sticks out too far isn't really a problem. A good thing about using reduced head flange nuts is that you can use a smaller (usually 12mm, but I see you can get 10mm wrench size M8 flange nuts too) wrench. All of this makes installing the header easier.

Me, I'd be inclined to leave any studs which behave when you remove the nuts alone. Breaking studs usually only occurs when trying to get the nut off, doesn't it? Having one fall out is unusual? Maybe when the thermal reactor were removed some of the threads in the heads were damaged, leaving the replacement stud or studs a bit loose? Those would be candidates for Helicoils or the equivalent.

Having one stud fall out ought not to interrupt a trip, should it? You didn't realize you had one missing? Might have been gone a long time? Low risk of interrupting a trip if one falls out?

Of course, those which feel loose ought to come out easily, which suggests a replacement along with the insert. And if you have them all out already, well why not new. But I'd not be inclined to go through the brain damage of working hard to get a stud out which resists removal.

[otto_kretschmer]

I tried taking one stud out yesterday. I double nutted it and found the stud was in tight. I changed my mind about replacing all of them with new and if it ain't broke don't fix it.

I had to replace the cam box/housing about 14 years ago so I had the headers off. Its possible I didn't tighten that nut enough. It was a long time ago. I did the clutch and alternator too. Then the car sat for a decade for some reason.

If I can register the car as a historic vehicle I won't have to smog it. Arizona requires a smog inspection for cars built after 1967. I don't think I can get many parts like the EGR valve. The reactors are gone, the tube from the reactor to the EGR is open.