if you have a torch, heat around the area where the stud is broken first, have extracted stuck exhaust studs from cast iron manifolds like that, just be more careful with the heat when working with aluminum.

 

I've used EZ Outs successfully, and I've also used Marvel Mystery Oil to free-up a rust "siezed" Ford 302 engine.

 

I only use Irwin Hanson or Vermont American. I been lucky and never had any problem.

 

I wouldn't say easy outs don't work at all, but you need to be patient. One thing that I have tried that works is, yes, center the hole, and gradually drill it bigger until there is a "thin" walled shell in the hole. The easy out will be the biggest size you can get in there, and it will usually get the broken stud out because at . heat penetrating oil helps, but not in that order.......I used to approach it as "try the easiest thing first" in order would be: left hand drill bit, then up size unti I figured Id be getting into the threads, then easy out with PB blaster, then heat, if all failed drill next size bigger, if I ganked the threads, I would install a heli coil insert.

 

There are a lot of things you can do to help yourself with broken bolts. After you get a hole in the broken bolt, heat if with the best torch you have access to. Handheld propane jobs will work, but a true oxy-acetylene torch with a small welding tip is the best. You don't need to melt anything, but if you can get enough heat in it to change the color you will have better results. After you heat it, let it cool a little and melt some wax on it. Shoving a crayon on it works. Hot wax will pull into the thread joint and wax doesn't burn off like a lot of the oils do. Let it cool down all the way so what is left of the stub shrinks a little. You may have to repeat the heat, wax cool cycle a few times but you can get nearly any of them out that way.

Fully agree with everyone who says that once you get an easy out broken off in it or just can't get it, bite the bullet and pull the head. A machine shop can get it out for not much money and do it right. I have a couple of milling machines and other machine tools and sometimes there is just no better way than getting things set up in a vise or solid clamps, getting truly centered on the hole and just cutting the broken bolt out then repairing the threads.

 

From a post some time ago now a guy made a big play on the fact the stud and thread are designed to lock such that the nut should come off and not take the stud out of the head so...

His response was to use one of these and then retap the thread to clear the rest of the stud.

https://www.jpcycles.com/product/440...campaign=41227