[supereal]

We remove broken studs by wire welding a nut to the end, if visible, or a bolt, if not. The heat will release the threads, allowing the stub to be backed out. Don't drill the stud, as you risk penetrating the water jacket. Common "easy outs" work by expanding the stud, making the job even tougher. If you don't have the equipment, find a shop that does before risking block damage. This procedure also works well to remove the usually broken exhaust manifold bolts.