Well I couldn’t get good thermal conductivity with my sensors so I shot the points I wanted to monitor with a non-contact thermometer. I see a max of 165 deg F at the thermostat housing after about 6-8 minutes of run time at about 1000 RPM. My cooling water barrel is far from ideal. The skeg is about 4-5 inches off the bottom of the barrel, should be virtually on the bottom. The reason I say this is the amount of air in the water near the water inlet. Who knows how much water vs air the pump is seeing? If time allows I will jack up the barrel but in the mean time I am happy with the temperature reading results so far. BTW I have a test wheel on the shaft, not a prop. The couple of times I have put the engine into gear water went everywhere! With a prop on, there would have been no way to keep water in the barrel! I keep a hose in the barrel to try to keep the water as high as I want it, that is almost successful but not really.
Right now I am trying to finish putting a graymarine fireball four 90 hp engine in my 1953 Mercury Ski Tug that I have been restoring along with the Thompson/ Johnson since Sept 2019. Split priorities, good thing I’m retired! Thanks Tom Alex
