Hi!
Why do you want to know???
It's just one of those unnecessary things to know! Just like knowing how many amps a glow plug draws...

I been a pylon racer for 30 years and I can assure you in the racing world we don't take any temperature readings at all! We just set our engines by ear! Simple as that!
Our airplane glow engines just run at full power for how long as you want to , and you don't have to take any temp reading to know if they are running too lean or not...they are made that way! The temperature spektrum is very broad and as such our engines run just fine at very different setting.