I know there was a lot of past posts on exhaust studs, but didn't find this one covered.

I removed the exhaust headers on my '75 1.8, and it didn't occur to me at the time I was taking it off, but I was using a 1/2 socket as the 13mm was loose and 12mm didn't fit. One stud came out (cleanly and easily). When I looked it up online, I see that 1.8s should have a 9mm/8mm stud, but the one I took out is the same thread on each end. My metric nuts that I have for the "new" exhaust will start on the stud, but bind up on the threads.

Rather than replace all the studs with what is supposed to be there (and no doubt having to rework the threads), I'm thinking about buying some new 1/2" nuts, cleaning up the threads and putting it back together as-is for now. I figure this can be fixed properly when it's time for a head (or complete engine) rebuild...which may not be too far away as I don't know anything about this old engine's history.

Reasonable approach?? (realizing that I'm on a budget, and the budget priority is getting the body/paint done first).

hmmm, no. Factory studs are 8 x 52 (or 56) mm, I could look the length up in the PET or you can log onto the PET using the link in my signature. Step studs (8mm/9mm) are when you strip the threads in the head and have to helicoil or timecert the head with the next size larger threads. Use the correct copper exhaust nuts which I seem to remember are maybe 12mm wrench size; that seems to jog my memory because of the very rare use of 12mm anywhere on a 914. I would recommend going with factory sizes.

The 8mm/9mm stud is a REPLACEMENT stud, used when it is possible to retap the hole to 9mm. Not very likely, IME. Do yourself a favor, use the Porsche Classic Parts catalog, available online as a PDF. CDs are also available from your friendly local Porsche dealership for under 15 bucks. They can order it for you. looking up things like this online exposes you to drivel posted by people who know as little about it as you do. BTW, if you use inch nuts on metric studs, you're more than likely to create a disaster. Describe the metric nuts you have on hand. Are they 8x1.25mm? Are they locking nuts? Like maybe those copper plated ones everyone (except VW and Porsche) seems to love? Just dress the threads of the studs with an 8mm x 1.25 thread chaser and see what happens. (NOT a die, a thread chaser!)

Get back to us on that.

The Cap'n

the exhaust studs are known to have potential for nightmares from being over tightened and stripped. do not over tighten.

I don't know if anyone uses anti seize on them into the head, probably not, as most of the time the stud stays in the head.

nuts ( I think they are copper color coated ??) $0.75 each. I think it is the only one pelican sells.

http://www.pelicanparts.com/catalog/shopca...p_pg1.htm#item3

post some pics of what you removed.

see exhaust stud here - both step down and standard shown here - hopefully you don't need step down and all your head threads are good.

http://www.autoatlanta.com/Porsche-914-Exh...Studs-srch.html

jim

ps: can't go wrong listening to krusty

Ok, I may not have been clear on my explanation...the nuts I took off the car, put there by a PO are all 1/2" (shown at top in pic below). The ones I have, that came with a complete (backdated) exhaust setup from someone else here on 914World are metric (bottom one). The metric nut binds up on the one stud that came out of the car...so, I'm assuming they are SAE studs (since the SAE 1/2 nut fits). The new nuts appear to be hardened steel, not the copper ones (that I recall reading the Cap'n does not endorse).

So, my thinking is to fix studs later, but for now just replace the rusty old 1/2" nuts with new, hardened steel ones since they fit (and the threads look clean as shown below).

I haven't crawled back under the car to try to inspect the condition of the threads where this stud came out, but it felt normal (smooth) when I backed it out.

Click to view attachment

my guess is PO basically rethreaded the studs when he put the sae nuts on?

the sizes are definitely very close.

does the nut go smoothly on both ends of the stud?

gently using fingers, not tools?

I believe it was the AA web site where I saw that 1.8L used the 8mm/9mm, so I will remember to check the authoritative source next time. Thanks!

I'll have to wait until I get a thread chaser to verify the threads...I got a bag of stuff from another member, who I believe sourced the parts from 914LTD. I only know they are metric.

Yeah, that's what/how I tried to check. The metric nut starts, but binds up in a couple turns. The 1/2 nut goes on smoothly on both ends of the stud, and the stud threads look fine as well.

a random thought - it seems that cv bolts are 8mm though I do not know if it has the same thread pitch as an exhaust stud, and I found a regular steel nut that I think was probably used on an exhaust stud at one point in time, and it is 13mm, fwiw.

Thanks, I have my stuff in a baggie, and will take it to a local hardware store where I can verify what I'm trying to fit on the stud. For what I have, I can only verify what size wrench fits. The old nuts that came off are all in good shape, too (no rounding).

Trip to my local ACE hardware today confirmed a couple things...

1) the studs/nuts that came off the car are exactly what they are supposed to be

2) my tools are crap, as my Stanley 1/2 inch wrench fits metric nuts perfectly, and the metric wrenchs are a bit loose.

Not sure what threads are on the hardened nuts that I got with the exhaust "kit" that wouldn't go on easy...so they're going in a bin for now. Ordered some new studs and nuts today.