Advice on extracting broken bolt from mag case?
 

I'm doing some freshening up and an ignition upgrade on my EFI 2.7l motor, and ran into a little problem while removing the engine tin. All three of the m6 bolts on the driver side snapped off. I was using a 1/4" ratchet and didn't use much force. The first one snapped off so easily i thought it was a fluke. The second was the same way, even though I was being careful. And I say "snapped off" but there was no "snap" - the heads twisted off like they were class 0.0 from harbor freight.

I heated up the third bolt with the mapp torch (acetylene is empty), but that one broke off easier than the first two!

So I soaked them overnight in PB blaster, with the engine tilted 90 degrees to let the oil pool above the broken studs. I still managed to break off one of these double-sided bolt extractors.

So... these things are STUCK.

Anyone have any hints or tips?

I replaced all of my extremely rusted exhaust studs last year and managed to get by without breaking a single stud, so this isn't exactly new ground, but I've never had a bolt so throughly seized in a mag block before. And these are really short bolts!

If I drill the studs out, is there enough room to step up to an M7 bolt?

Yes, I'm an idiot. The heads are Aluminum.

Cam tower. 6mm timerserts are the best bet. Center punch dead center and use a very small drill bit first, then the drill in the timesert kit

I broke some of those off, I think I carefully drilled progressively larger and then carefully used a tap to clean the threads.

Yeah, I had to drill out each one. The broken extractor was a huge pain. I ended up using a carbide spade bit to drill out the extractor, and then my drill went off center... huge mess.

The other two bolts weren't bad. Every other bolt came out without any issues. I think I'm going to replace them all with stainless steel when I put it back together.

A touch of anti-seize won't hurt either. Glad you were able to get the out without having to resort to using a EDM machine!