Lead Balloon
What is your theory on why valve temperature goes DOWN as the mixture is further leaned past that point - whatever it is - and EGT continues to go UP to peak?
I gave the explanation in the very same post. But here it is again
Easy: the spread between where CHT and EGT peak as a function of mixture means the valve temp will not peak precisely at either but between them.
It is a no brainer. The observation that exhaust valve temp - as a function of mixture - begins to fall slightly rich of peak EGT does not in any way invalidate the theory that valve temperature correlates with some combination of CHT and EGT. In fact, as the working fluid is the heat source and the cylinder head is the heat sink, it cannot be otherwise.