Dam. Brutal crew here. Lol. I haven't tried. Grand sport dropped the motors in the cig. Said they couldn't get them out. Pfaff put them in , so I'm third party here. Lol. I'll forward the techniques to grand sport marine lol.

I'd just heat them up with a propane torch. No need to get carried away with heat, its just brass.

Be careful though, I had brass fitting break off in the block, and its a pain in the dik to try and get the broken pieces out of the threads, when your in there like a monkey wedged between two engines.

With those brass drain plugs, some guys get carried away. On regular blocks, there isn't a ton of room behind the plug. So they tighten the chit out of it, thinking they are snugging it up real good, but what they may be doing, it bottoming the plug out against the dam cylinder wall, and jamming it like a dam set screw..

Any luck getting the plugs out? I was serious about the hammer trick.