Thermostat question

Actually there is no rock solid explanation of what a thermostat change will do for you until you do it. IF you have one that is defective, sticking open or closed etc. I had a 440 Demon that was fine until you stopped, fan and shroud were good, 3 core radiator all in good shape but, pull into a drive through and it would boil over. I put vent holes in the fender wells, blocked the bypass, 165 T stat. Still no luck. Put a 195 T stat in it and it ran cooler in all situations than ever before with no more boil overs.