Exhaust manifold dilemma

[SemiEvolved]

Need some advice on whether (or how) to fix or replace my exhaust manifold. PO retapped and replaced original collector studs with 3/8" bolts. We broke one bolt when pulling the exhaust system out. Long story short, the extraction didn't go well and we tried to JB Weld a new 3/8" stud into place. The JB Weld didn't hold as I was reinstalling the exhaust so now I'm left with two good 3/8" studs and one stripped hole.

Options (as I see them):

1) Try to get someone to weld in a stud with the manifold still in the car.

2) Pull the manifold and replace with used OEM.

3) Pull the manifold and replace the entire exhaust with aftermarket.

4) My father is trying to convince me to retap the stripped hole to an even larger size (1/2"?) and use a two-headed stud (1/2" on one side, 3/8" on the other). Not even sure if this is possible or if this stud exists.

Does anybody think option 1 is even remotely possible? Am I missing other options? How difficult is it to pull the manifold?

I'm willing to go to extraordinary lengths to not pull the manifold because I'm concerned about the overall difficulty of that route. It's probably within my capabilities, but I'd like to avoid it in the interests of time.

Thanks in advance for any input!

Edited April 16, 2013 by SemiEvolved

[cbuczesk]

Can you drill it out and just use a bolt? Maybe a picture would help.

Chuck

[beermanpete]

Use a Heli-Coil insert. They are available at most hardware stores and auto part stores. The "kit" comes with the correct drill, tap, insertion tool, and several inserts. When properly installed you will have new threads that are as strong or stronger than the original. Check the size of the existing hole to be sure the 3/8 kit will work. If not go to a 7/16 or M10 thread as appropriate. If you are careful you should be able to install the Heli-Coils with the manifold on the car. I suggest going back to studs and nuts when finished. It makes it easier to install the exhaust pipe.

[SemiEvolved]

Thanks Chuck. I'm trying to go with an option that gets me a stud rather than a hole for a bolt. If and when I need to pull the exhaust again, a stud/nut combo is much easier to work with and less likely to strip out again. I unfortunately didn't take a picture of the stripped hole before we JB welded the stud in. I should have, because the area damaged during the extraction of the snapped bolt was substantial. I wasn't clear on that, but about 60% of the original threads were damaged.

And thanks for the suggestion, Pete. I may investigate that route if Option 1 is deemed unworkable. A heli-coil seems like it might be better than option 4, though I'm nervous about using one in cast iron.

[beermanpete]

Why nervous about using a Heli-Coil in cast iron? Cast iron machines and taps easily and the thread insert will hold as good at the original thread if it is installed correctly.

It seems you want to weld in a stud but I am reasonably certain the factory stud is a threaded in. Welding cast iron is far more difficult that drilling and tapping it and can't be done correctly while on the car.

[SemiEvolved]

I've done a couple heli-coils in aluminum, not cast iron. So just lack of familiarity with the materials involved makes me edgy. I'll take your advice to heart and prioritize re-tapping the hole, either for a heli-coil or a larger stud, and give the welding a miss. I think I was getting too invested in a "quick fix" and I should have more reasonable expectations.

Thanks again!

[cbuczesk]

I'm with beermanpete. Do the heli-coil if you can access that area. It should be pretty quick and easy! :-)

Chuck