Re: bench check merc 1150?
Have you determined that your existing powerhead is no good?
Make sure you consider the year of the replacement powerhead. Yours is a '72, which has the older bolt pattern and exhaust divider at the base. You cannot bolt a newer powerhead ('73 onward) onto your mid-section.
Whether or not to buy a used/rebuilt powerhead is a tough decision. I'd recommend removing the intake covers for inspection. Watch for scored/broken rings or piston skirts, and do a compression test if possible. Even better would be a cylinder leakdown test. If it already has the carbs removed, have a look in the openings for the reeds. What you'd be looking for is any reed plates that arent sitting down flat. Lastly, to check for worn bearings you can use a long screwdriver in each plug hole while rotating the flywheel. Just as it passes TDC for that cylinder, try pushing down on the piston. If you detect significant movement (click) you may have worn conrod bearings. Being a rebuilt motor you should not see any of these issues.
My 2 cents. Other's opinions may vary.
