JP, I have one of their single CHT gauges also. It is a very nice piece, high quality.

Coming from the Aircraft Industry, also a certified Airframe and Powerplant Mechanic, working for a high performance twin engine (N/A’s and Turbocharged) complex aircraft manufacturer. The Aerostar series. Working on the flight line as a crew chief getting an aircraft ready for first flights, testing and recording flight data, setting up real world conditions the aircraft would be flown. Differing percentages of cruise power. All this to achieve certification. Making it a real airplane as recognized as legitimate to be sold aircraft under FAA rules.

When a one sets up a cruise power, the mixture is generally set 100 to 200F rich of peak. So, from full rich in 100% power, maxed out, one pulls the throttles and prop speed back a once that is established as your cruise power, the mixture controls and leaned to peak EGT and the richened to drop the temperature. Fuel rich of peak.

The difference between a automobile engine and an aircraft engine is that automobile engine speed varies all over the place, on the other hand, aircraft engines because the are not directly coupled to transmission engaged to the road, they can be adjusted to a constant rpm and mixture.

Given my experience in aircraft and also a Aerospace Design Engineer with Lockheed, I would never ever consider using and EGT to adjust an automobile engines mixture. I would use it to monitor, but never as a point of data to trim a mixture.

A CHT is generally to slow to react and not a good source of data to do the same. The only accurate way to effectively trim fuel mixtures is a Lambda Sensor or O2 sensor. That to has some lag time if using a wide band sensor. A narrow band IS the only way to effectively truly tune. The days of reading spark plugs is kinda out the window as well. With leaded fuel it was much easier to read.

Another hobby of mine was blown alcohol dragsters and gas altereds. Reading plugs on those was predictable.