Cylinder Head Temperature gauge

As the engine works at high speed or uphill, head temperature will increase quickly.

An air-cooled engine requires a steady flow of air for cooling.

[1] The CHT sender usually has a K-type thermocouple that is mounted under the spark plug.

The K-type thermocouple is a pair of two dissimilar metals that produce a small voltage signal when heated.

The error can be corrected with a cold-junction compensating thermistor, which measures the temperature at the cold junction so the gauge can adjust the reading.

Analog Cylinder Head Temperature gauge
A cylinder from an air-cooled aviation engine, a Continental C85 . Notice the rows of fins on both the steel cylinder barrel and the aluminum cylinder head. The fins provide additional surface area for air to pass over the cylinder and absorb heat.
Flat-four aircraft engine