Thanks for the info, guys. The engine is from a donor car we've been using and I know nothing about its history I was removing the head when the bolt broke. One of the other bolts had a sizeable amount of rust around it and in the hole when I removed it. It was tough to get out and I'm probably lucky that one didn't break.

The specific bolt? - it's the one closest to the firewall.

I'll get some Blaster and start the process. I assumed a few days would do it, so I'm glad you guys gave the advice to keep it wet for a long time. My fear is breaking the blasted thing. The work itself isn;t too fearful.

This donor car has been a real treat. The kid bought it for $200 and the owner said it wouldn't run and the engine had made a horrible "knocking sound" or clatter. Someone had replace dthe clutch not too many miles before it quit running, and the cylinder walls, on first quick examination, look pretty good.
The kid has gotten a lot of good stuff from the car already.

Again, thanks for the help.

Jim Hampton