Hi Guys,
After an extensive search lasting a good few months, I found an untouched GX Head.
New guides and seals fitted, new valve seats, new valves. Then fitted it. Found a small leak at the rear welsh plug. In the process of taking the head off again to fix the welsh plug, then I broke one of the studs off. Tried with a vice grip and wrench to get the remaining stub out but it then broke off flush with the metal surface. OK no problem drilled a small 6mm hole inside the stub to get it out with an easy out.

I never knew steel could adhere to aluminium so strongly as the other studs came out very easy.I liberally applied penetrating liquid and left it for more than four hours to penetrate.Then heated it with a torch to get it out, and in that process I managed to break off the easy out again inside the original stud flush with the metal surface.... It wont drill out as the metal is probably even harder than the drill bit itself . I have tried tapping it with sharp punches to get it to turn. no luck. I have even tried to cut a 2 mm crosscut in the stub to get it to turn with a screwdriver, 4 stuffed screwdrivers later no luck.

I am outta ideas/plans to fix this....Please help !!!!!!!!

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crikey. You can drill it with a large drill bit, then fit helicoil to repair the threads. Using a drill press might be best, drill it all the way down.

They don't only adhere, the metal can migrate and form a chemical bond. Strange that only 1 would do that but afer 40 years anything can happen.

I would leave it and utilise the alternate bolt pattern for your manifold. You might have to drill the manifold but it may save any further damage to the head. If that is an option your last bet may be to weld a piece to the stud and try again to remove it. ddgonzales is on the money though.

If you're anything like me you'd be hell bent on getting that stud out. A tungsten carbide drill bit should cut the easy out, be carefull with it though, they're a little bit brittle. Try smooth the surface with an angle grinder or something so the drill's got a nice flat surface.

When I get a stud like that I drill right down the middle and go up in 0.5mm increments. If it doesn't come loose before you drill it out the whole way then retap or put a helicoil in it like DD says.

last time that happen to me those stupid drill bits snapped, so i got a nut and put it over the top of the bolt and welded the nut to the bolt and that worked after a few goes

If you are gunna try and drill out the broken bolt and easyout then use a left hand cut tungsten drill bit (i know it sounds like another workshop prank like chequred paint but they do exist) That way when your trying to drill out the broken bolt the reverse cutting action will not only drill a hole but also try and unto the broken bolt. Worse case you are left with a hole you can helicoil best case it comes out after a few mm of drilling. Use penty of cutting compound and make sure you set the head up in a jig so its kept perfectly centered to the hole and squared off, good luck.

As lethal_john said, use a welder :)
The heat and currant does wonders to a stuck stud and the mild steel rod will not bind with the head. If you make a big mess you can still fit a thread repair insert :)
Someone with a TIG welder can also help to build it up and then weld a lever to it.
Drilling it out is not easy even if you have tungsten carbide drill bits.
The correct way is spark eroding, expensive as well :(

Best of luck!!

I am soaking it in penetrating oil for the meanwhile, ( while i muster up courage to tackle it again) Thanks guys !!!

LJ is the way Ive done it before with a nut over the top so the hole is just as big as the stud make sure theres no contaminants like oil lube etc. Then use ring spanner once it cools and should unscrew easily. Let head stud area cool before using a new helicoil.

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Are you talking about a heating torch? Or welding a nut to the broken stud?