The thermometers came in. I connected the spark plug thermocouple to it and temporarily connected it to an ac/dc 12V powersupply.
Fired the engine up (happy it was cold and had old gas but barked right to life) and let the temp settle at a fast idle. I didn’t feel like adjusting the idle for temp was necessary and thought leaving it a little fast would ward off a fouled plug for the test.
temps measured close to what my IR gun says.
I don’t know if 125* F is a “normal” temp for that condition. Seems to be working well enough. No weird effects from spark plug.
My thermocouple didn’t seal well enough. A little blow-by was on the head. So, I need to figure that bit out.
Anyways, It works. It was cheap. Time will tell if it last long enough to be a permanent solution.