Cyclic,

In an automotive engine exhaust gas temperature also varies all over the map depending upon where you read it.

Nevertheless I thing reading the temperature provides valuable information. As with any other measurement readings need to be consistent to provide information. Clarence Lee stated many years ago that the most consistent readings were thermocouple under the glow plug. Most will not have a thermocouple but pyrometers are inexpensive and available. Any consistent reading somewhere on the head is probably valuable for the relative temperature values.


And yes someone can screw up any measurement.

Bill