Add another vote for HEAT! As many of you know, I mostly delve into Mercury’s, and these have the dreaded exhaust cover bolts as well as water jacket cover bolts on Hurricane type blocks. These are sometimes just not going to come out without breaking them. I picked up a block from another forum member that came with 17 broken bolts in the block. I got them all out without drilling them. I use a TIG welder and build up a weld on the offending bolt until I can grab it with a vice grip. The heat from welding aids in loosening them. Once the head, exhaust cover, water jacket cover is off, you can have access to the meat of the area where the offending bolt is seized into. Apply lots of heat as quick as you can. This is where the acetylene comes in handy as you can add a lot of heat quickly and get out. I also have two propane torches. One gives a much hotter flame, so get a good one if you want to use propane. It can work just fine with a good torch assembly. As for the OMC head bolts, I agree that often the bolt is seized into the area around the head itself as well as the threaded portion.
Steve
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