Engine valve is one of the most important parts of an engine. In order to assess engine valve's reliability, it is necessary to predict its in-operation temperature distribution with a high degree of accuracy.Conventional methods for predicting a valve's temperature distribution had particularly poor generality and accuracy. After much testing, we have collected data on how valve temperature reacts to changing engine operating conditions. We learned from this data that the key factors in valve temperature distribution are ignition advance, air-fuel ratio, and engine speed. We were also able to use this data to optimize the heat release pattern and heat transmission coefficient used for predicting valve temperatures. This allowed us to make the prediction of valve temperature responsive to changes in engine operating conditions, general, and highly accurate. In this paper we discuss gasoline engines; this system is also applicable to diesel engines, but we believe that further testing and evaluation will be required before we can proceed with implementation.