I heat them red hot first and let them cool. I use a Snap-On stud remover with a collet designed for that thread, tightened as tight as I can get it. Then I let a 1/2" impact "lightly" hammer on it to break the bond loose. A breaker bar and socket will just twist and break them. You want that light hammering too loosen them. It's not a good feeling when the very first one breaks. 45 of them came right out and three broke.
Then I mig weld nuts to the broken ones. Grind the plating off the nuts and washers or buy un-plated ones. The plating contaminates the weld, and it won't be as strong. We did this at work a lot on the trucks and we found we had better luck by removing the plating. Two of them came out by welding nuts to them and one refused to move I broke several of the welded nuts off. As you can see it's hard to get the mig wire down in there that deep to get good penetration on the stud so first what I do is weld a thick washer to the stud and then weld the nut to the washer, filling the entire void in the nut with weld so that heat will travel down into the threads. Then let it cool before trying to remove. The mig weld will not stick to the cast iron, no worry of messing up the block. Not everybody has a mig welder so that leaves the drill. You can see how the coolant (actually lack of the green stuff) got around the stud and the electrolysis and corrosion ate the block. It also glued that stud to the block.
I just got a call and need to leave but I will post more photos of the welded studs and the drill guide bushing I use to take out the one stud. Oops! I forgot to comeback yesterday.
You can see its wet around the base of the half-out stud. It started to come out and stopped and wouldn't budge. I heated it and melted some wax which wicked down into the threads and then came right out. You can see that the mig weld did not stick or damage the block and I'm not that good of a welder. Infact I'm a one-eyed welder after Lasic surgery destroyed my left cornea, they cut too deep. I had to have a transplant and now I can't see anything out of that eye. I can see, I just can't see the eye chart, not the letters the fricking chart. It's all about taking your time and being patient with this stuff. Slow is faster in the long run.
The bushing is from a Snap-On extractor set. It has all kinds of bushings, bits and extractors. Bolt the head on, drop the bushing in there and it's impossible to not drill the center of the stud. I removed the head and drilled it with two more "sharp" bits leaving just a shell of the stud and it came right. I finally bought one of those Drill Doctor bit sharpeners, it works pretty good.
