[36tbird]

My simple theory is that if you have a clean system, rust and casting sand gone, then you should achieve a system temperature very close to whatever thermostat you have installed. Now, there will surely be a flurry of comments on whether or not you should run thermostats, whose water pumps you are using, fan type fan shroud, yada yada yada.

I'll just tell you that I live in the same climate as you and my '36 pickup with an 8BA that has 180* thermostats, no fan shroud but the big 19" 6 bladed fan, distilled water with water wetter is running around 180* all day long. On the new engine I am just getting to run, a 59A with 180* thermostats, 6 bladed fan mounted on the alternator with a home-made fan shroud, running it in the garage without any extra airflow it is holding around 150 on 3 mechanical temp gauges. (I am completely befuddled as to why it is running so cool.)

So, I guess I am trying to tell you, there is no easy answer to your questions but there are dozens and dozens of theories.