Multiple Broken Exhaust Studs
 

First off I've got the jig to drill out the studs. My issue is I have both studs broken off on a couple of ports, so I have no way of bolting the jig down. Any suggestions?

I did that on one of my ports, I was able to get the jig tight into the exhaust hole and worked really carefull to line the drill hole up, as long as you are careful and keep checking you should still be able to get the bit started, use plenty of cutting fluid and check your work frequently.

Or..you could start with a smaller drill bit and get it started ensuring you are dead on center.

Is the engine still in the car? What jig are you using? Is it the one from Christian?

At worst you may have to drill, put inserts and re tap the holes.

left hand drill bit and one size small may be the trick if you can't clamp very snug ...
and as the other poster ???'d motor in or out ? if out you could rig an angle iron with bolts spread and a bore hole in the center and cross clap down to lower legs of engine stand or to bench if bench mounted ........

The motor is still in the car...

Motor still in the car presents a few problems but can be overcome.

Carefully grind the stud flush, make a deep mark with a center punch in the center of the stud.
Drill with appropriate size drill (Left or right) making sure that the drill doesn't wander.
If it does, stop, go to the opposite stud and repeat.
Staying in the center and keeping the drill straight is critical.

You have to find a way to get enough push behind the drill motor so the drill can make chips.
Finish one hole, install a new stud, install the jig and finish the other side.

Protect your eyes!

I just replaced all the exhaust studs on my car, but my circumstances were better that what you are describing. The engine was out and only one of the studs was broken off. You didn't state if they were broken flush with the head or if they were sticking out enough to allow you could get any type of grip on them.

If they are nearly flush, I agree with Gunter that you need grind the edge flat, then hit the center with a punch. Hitting the center is THE key step. Even if you use the jig, you need to hit the center with a punch. I am not sure how much value the jig will be unless you can tighten it down. The hole for the bit on the jig is almost the same size as the stud, so you have to be almost perfectly centered not to hit the female threads in the head. I was successful at drilling mine but ended up having a helicoil installed because my tap seemed to be slightly wider than the stud and couldn't get the stud tight. Drilling is much more work and higher risk, but sometimes it's the only option.

I would only drill if you don't have enough stud protruding to get vice grips on it. I actually had to get two pairs of vice grips on mine because a single pair kept spinning. The stud needs to be cherry red, MAPP gas is a good option. If you can get it to move at all, stop and reheat the stud, turn, repeat as necessary until the stud is nearly out.

http://forums.pelicanparts.com/911-engine-rebuilding-forum/512581-top-end-reseal.html

not to doubt the vice grip idea but if it sticks out far enough to grab with vice grips why wouldn't you use a stud remover that is made to grab something round and you can still use a torch to heat assist just tighten remover , heat , insert ratchet and turn .....

Or the other way to make it easier .......take the motor out. there has to be something on you "when I need to take the motor out I should do __________ list"