All, thanks for the great responses to my plight. I have been busy and haven’t had time to do much or check this forum. Really appreciate all the responses, especially from mistralseattle and rich steiger.
I would never have guessed the ratio would be 2.63, but when my engine was running, my boat typically did about 7 knots at 2800 RPM. That is just about hull speed and I rarely exceeded 2800 RPM. My trans is KM4A #6078. We assumed that #6078 is the serial #? My next steps were a call Hunter and possibly pushing the prop shaft back to remove the trans. I was digging out my original owner documents to try and find the engine serial number, the plate is missing. But I think mistralseattle’s info sounds correct as the RPM to speed thru calm water matches my experience perfectly.
Rick, in case this might help someone else, here is my problem as I know it. The engine seized (water rarely gets below 80 degrees F out here) once before and I had someone rebuild it. We found that the wall in the elbow that mixed heated seawater with exhaust to blow out the exhaust had rusted through and when the engine was shut down, seawater dripped back into the first 2 cylinders. We replaced this elbow along with all pistons, rings, bearings, valve seats, etc. Thought that fixed the problem, but apparently sea water is getting into the cylinders from another source. Given the time, effort and $ (at least $4K to $6K) to rebuild the engine in the salon, I think a remanufactured engine is a better solution. Not sure we know enough to be sure we find the real problem. I can get a remanufactured engine for about $7K plus shipping (another $800 or so).
Not really sure what caused the engine to seize, but pretty sure it is sea water getting into the cylinders. Never ran the engine without oil, never overheated. Just seized after sitting up a while and the previous rebuild showed without a doubt that water had gotten into the cylinders via the exhaust.
Really appreciate all the help. I will post status later.
Thanks much to all.
Roger
