Reply to "Snapped bolt in block - how deep can this be drilled?"

Perhaps you could measure the center to center of the holes and the location of the dowel (or maybe use the old bracket as a template, I can't picture it so I'm not sure), find a piece of 1/2" (or whatever) stock and drill it to to act as a guide to keep your drill square and on target?

The hole in your temporary guide (for the hole you need to repair) would be left at either the size of the repair tap, or maybe 3/16" to use as a pilot to drill out to the proper diameter afterward.

Bolt that up to the engine and drill through it. I think it would help to control wandering. As far as depth, I would guess that you could go the same as the adjacent holes, though I'm not positive about that. You should "feel" it when you're through the steel bolt and hit the cast iron. Looks like water back there.

Another thing that often works are the left handed drill bits, as above. If you're lucky they bite into the broken bolt and spin it right out. I have had no luck with the so-called "easy-outs".

Nasty job digging those broken bolts out, hope it's not hardened.