Broken manifold stud removal

Been working on rebuilding a XJ11 this week. Just finished installing the cylinder head after new guide seals and a valvel lap. I was putting the first carb boots on and the screw got a little tight. Tried to loosen it up and the head snapped off. I still had about a 1/2 inch of bolt there so I weld a nut onto the stud . Well it broke also leaving me with only about 1/4 inch. I'm going to have to drill this one out.

The biggest problem drilling a broken is keeping the drill centered. I thought about it for a while I had the bright idea to make a drill guide to help. A few minutes with my benchtop lathe and I had a guide. It is threaded on one end to screw onto the old piece and centered bored to keep the drill straight. I was amazed how well this worked. The hole is perfectly centered.

I still have more work to finish getting the stud out but this was a great start.

 

That's awesome, wish I had that a few weeks ago. I also welded and ended up still breaking off close to the head. I bought one of those long multihole drill guides, works well but the long shape makes it awkward in some situations.

 

MLEW, what are the dimensions of that thing ?

 

1/2 round rod with a 1/8 pilot hole. Other end was tapped to fit the stud. After screwing it on the broken stud I drilled 9/64 then 5/32 and so on until the guide fell off. Then drilled for a thread insert. It kept the hole centered nicely.

 

Did you have to re-tap?

 

If you have a set of metric drills you can carefully drill out to the minimum diameter of the threads on the fastener, and pick put the rest of the fastener's threads with dental tools. That only works if the threads have not become hopelessly coroded to the head.

 

Mine are superdidooper corroded. That's why I was asking. To see how the process went for this bike

 

Did you try to easy-out the bolt after you drilled with a 5/32 ?