[OCCOBRA]

The radiator is designed to flow at a given rate or at least within certain parameters. The design is based upon type of radiator material, number of fins per inch, number of cores wide, and number of passes. In short the radiator offers a certain number of square inches of heating surface. Now you throw in flow rate. Too high a flow rate will not allow each square inch of heating/cooling surface to absorb and transfer the engines heat. Basically you need enough transition time to absorb/transfer the heat to the radiator, and then to the air. I see this all the time in my line of work (boilers). The physics are the same.
I tried Evans coolant in a 428 Mustang and had coolant creep through the gaskets. Also straight Glycol (Evans) has a much lower heat transfer coeficient than water. The reason people/racers like Evans is that the product at attmosphere (o psi on radiator cap) will boil at 375 Deg F. Therefore should the engine develop a hot spot there is less chance of Flash (Steam )
Check a freinds car (That has no heating problems) that has same size engine and radiator for temp inlet vs outlet. This "Delta" should be your target. A high flow thermostat will probably not flow too high to cause a problem, but running without a thermostat or restrictor disk will!
I am new to the Cobra world just having purchased my first 427 SC (FE). Anyone in Orange County Ca. please give me a call @ 714-401-6054
Dane