What kind of motor are we discussing?
Does it have a coolant bypass system in place? The job of the bypass is to allow some coolant flow into the radiator so that the remaining coolant in the top of the block and heads doesn't go to steam, it also allows the thermostat to sense the coolant temperature.

An old rodders trick was to drill a small whole (less than 1/8") on the flange of the thermostat, this did 2 things, allowed air to pass into the radiator and allowed the thermostat to "see" the coolant temp faster.

Something to think about along with all the topics already in progress right??? ROFLMAO!