My 216 last summer in Misery heat ran an indicated 190-200 on the guage all the time. Numerous checks with thermoter in radiater said 180. 180 thermostat, pickup for the capilary tube is close to the head and I assume it is a little hotter there. Ck and see what your true water temp is. I had reversed flushed the entire cooling system and radiator twice. Truck never boiled over. I bottle of water wetter will lower you temp about 5-7 degress also.