spent many years working in water treatmeant plants as a industrial mechanic/machinist/welder.3 waste water plants and 1 potable water plant that had a small hydroelectric facility that made power to run that plant.waste water plants have issues with nuts and bolts rusting together or bolts rusted solid in their threaded blind holes.steel bolt in a aluminum head? if so electrolysis.you might try this technique that we used all the time when faced with this issue. put a small tip on a ox-acetelyne torch and get a cup of water handy.heat the top of the stud untill its red hot then dump the cup of water on top of it. let it cool down then do it again. warm the head up around 150 degrees and spray pb blaster or liquid kroil ( we kept a lot of it in stock at the plant) into hole and let it sit for awhile.what you are doing with this process is heat shrinking.once heated up to red hot then hit with cold water the stud contracts and breaks the rust bond as well as reduces diameter a small amount which relieves the torque applied to the threads as well.lots of times the fasteners were now easily removable sometimes by hand. a tig welder is useful in a situation like this also.one of the guys in our maintenance dept shared this trick with us.he learned it from a navy machinist who dealt with stuff like this on ships that spent all their time in salt water.once you break the corrosion bond in that blind hole it should come out easily with a easy out.you want the smallest torch tip you have and place the tip of the heat cone on center of stud only. if you get carried away with heat you could damage your cylinder head.used this technique many times in 40 years as well as shared it with other people.it works very well. if you can't get it to break free a vertical milling machine or a quality drill press would be my personal plan b if that was my cylinder head.have lurked on this website for awhile and have learned a lot from every one. my time to give back and help out.i live in pine grove calif.if i lived closer to you i would help you remove this.i do own a large complete hobby machine shop on my property.all my neighbors have now figured out how handy it is to have access to my shop. the only thing i charge is a cup of coffee.largest lathe i own swings 26" in diameter.as well as a horizontal boring mill. hope this helps you out !!!! and thanks again to all the members of OPE who have shared their knowledge on this website and taught me a lot of stuff about chainsaws, chain sharpening, chainsaw milling.
