Removing broken rocker cover bolt, along with broken screw extractor
I'm in the process of doing a partial rebuild on my 351 Cleveland in my 77 F100 Aussie spec, essentially everything but removal of crank and pistons. The engine was locked up due to carbon and a tiny bit of rust in a couple of open cylinders but freed up nicely. I've finished cleaning up and doing the valve seats on one head, and working on the next, timing chain replaced with a good double roller, so it's getting there.
My problem now is that one of the bolts on the rocker cover snapped, so I drilled out the centre of the bolt with a view to using an extractor on it.
Got the extractor into the hole, gave it some lubricant, and started to slowly twist (by hand using a tap and die handle, not via a drill/impact), and ping! Snapped the extractor.
Sooooo..... what's my next option? The extractor has snapped below the rim of the head, so I could try putting a nut over the top and welding it I think, but there is about 1mm of space. Would welding damage the casting of the head given its location? I tried to see if I could drill out the extractor but its hardened and the drill bit didnt even touch it.
It's one of the long edge rocker cover bolts, I'm thinking its likely to leak if I just leave it as it is, and if I'm putting the effort into restoring my baby, I don't really want to just gob on some RTV and send it, I'd definitely like to have it done properly, especially when I bought a bolt kit to replace the old worn bolts!