My 455 has a 180 T-stat and stays at 180 unless it get really hot (95+) and I'm just ideling through traffic.
I might suggest this. * Verify your temp gauge as was stated. * HD 7 blade clutch fan as close to the radiator as you can with a tight fit around the shroud. Some people have luck with the electric fan and others don't. One thing about the engine fans and they can really blow the heat out of the engine compartment. * Have you investigated the crank and WP pully sizes? I know there are two or three sizes of pulleys for each *What type impeller? *A\C?
Some odd ball stuff that I have seen in the forums over the years was quench distance (Head to piston), radiator height, timming advance and Lean condition.
