The proper head temperature occurs when the engine is warmed up and is adjusted at about 200 to 300 rpm below peak. A TT40 generally takes several seconds to come up to temperature and you can tell when it gets there because it quits gaining rpm when adjusted as above. The head is now at the correct temperature what ever that may be. Out of curiosity I have looked at it with one of those little but very inaccurate IR temperature gages and yes the readings were about 230 to 240 degrees F. Even if the little gages were accurate I don't know how you would use the information. I mean if the engine was properly adjusted to just a little below peak I certainly wouldn't start squeezing on the needle get get the head temp to 240. Maybe there's some guys out there that use head temperature to help determine optimum head shim thickness but I doubt it.

Denis