So I think I may have a stripped exhaust stud. I tightened them down last Tuesday to try and get rid of some popping on over-run. I was careful with them when I tightened them down. Only one was sort-of loose. I think it might be shot. Because it hasn't really improved.

JBugs has 9 to 8 and 10 to 8 replacement studs. The lengths are correct for the TIV. What should I get? Any other advice?

I do plan to drop the heat exchangers, make sure that they are true-flat and put in new (again) copper gaskets when I do this.

TIA

There's a lot of this going around. If it's still loose after you tighten it, it's pulled. Meaning, the 8mm stud has broached an 8mm hole in the aluminum head. And it's not a very clean hole, since an 8mm thread is not intended to be a broach (not sharp).

So that means you should go with the 8/10mm step stud. This is because the minor diameter of a 9mm thread (diameter across the low points of the thread) is smaller than the ragged 8mm hole you have, which means a 9mm thread won't get full thread depth and you'll probably just pull it again. Don't ask me how it came about that I was compelled to do this analysis!

Other alternative- 9mm timesert with 8/9mm step stud. The tap for a 9mm (inside thread) timesert is about 10.5mm, so you get good bite of the insert into the aluminum there as well.

Jim

I pulled one of mine some time ago too. I used a 9/8 from a bug shop, tapped the hole and it worked well. Do a search and you'll find my thread and pictures.

T

I drilled while on the car and helicoiled it ...........

So Joe, no not that Joe, the other one, no not that one either, yeh ... that one, if you want to borrow the tool you know where it's at.

The outer threads (not the ones that screw into the heads) on my heads seem to be a little worn, but I'm afraid i'll strip the head if I try to remove the studs from them. Am I too concerned about that?The heads are off so I can get easy access. Any hints?

I had 2 or 3 helicoils on the exhaust studs in my old 914. It seemed like I was forever having to drop that engine for some reason or another. The combination of old heads and rusted studs resulted in loosening of the studs. I remember it being a pain to install the helicoils while the engine was in the car, what with the drilling, tapping and inserting, but they held very well once buttoned up. Keeping that car running on a budget meant investing more time than money.

I went with the timecert and a 8x9 step stud. Retapped it with the engine in the car. Not difficult, just scary to do. Wear eye protection, go slow and make sure you have a 8x9 step stud that really is an 8x9 step stud. I bought 2 from two different suppliers before getting one that actually was the correct one. TYPE IV store has 'em.

Good luck!

Also per Jim's suggestion I tightened the exhaust stud bolts to 14 lbs instead of the recommended 18.