I have a 1969 B body with a built 440. Has about 550 hp. Removed the thermostat and engine still wants to run at about 200f when the ampiant temp. is about 85. Water pump flows really good coolant through the radiator. Engine does have large 2.5 in primary headers. All coolant is new plus running a cooling additive. last summer car ran no hotter than 185f.