Re: pristine 9622a (1966 9.5 Sportwin) – update

[Don]

I’m assuming you have removed the gearcase to ensure it is not froze up…
I like your plan about removing the intake manifold, that might answer some questions. I would be real careful trying heat to free up the powerhead, that may create more problems. This powerhead should probably come apart if it is stuck this good. You will probably do more damage if you get it freed up and then run it that way.
Sure hope I am wrong and that you find a simple explanation!