[Cool53]

Moose asked before about electric water pumps and I replied I use them on everything. That really keeps cavitation down at high engine speed, which helps control cooling. Cavitation is when a liquid changes to a gas. Just like the old days with vapor lock. That's why it's best to have a fuel pump push, rather than suck, and make sure the suction side is unrestricted.
I am going to get yelled at for this next piece. I run my engines almost as hot as the new cars. Trying to run cold creates a big quench area at the area where the top of the piston is thick, and gets constantly cooled by the cool cylinder wall. The quench are is often cool enough so that when fuel touches if during the intake charge it confess. The causes a lube issue, increasing cylinder wear, and increases carbon buildup. This carbon can get to where under a load it can provide a secondary fuel ignition point. That means detonation, which ain't good. So running a hotter engine helps reduce that issue.
Another thing regarding the cooling system us the coolant itself. A conventional antifreeze mix needs to have the pressure raised to the 15# range to get the boiling point. Coolant such as Evans NPG+ doesn't boil, with no system pressure, until around 375 degrees. And it provides a much more uniform thermal blanket, reducing hot spots, thus reducing detonation. With proper ignition control, aluminum heads, Evans coolant, and an electric water pump I can run 11.5/1 compression with pump fuel, and no worries at all. Unfortunately you can only run Evans in a clean system, and you run it straight, and it's pricey, but it last for damn near ever. So running on the highway I see between 210-220 degrees. Perfect. I know the old rule was to run as cool as you can, but then you lose power and economy. And with no pressure no one gets sprayed if a hose let's go.
I also run the electric water pump and cooling fan so that if the fan turns on after the engine is shut off it then turns the water pump on. This makes my engine much cooler than your cool engine, after shut off, reducing damaging heat soak, which can reach over 260 degrees.

[themoose]

Jef

You talk about the need to have a clean system in in order to be able to run Evans. Does that mean a never used pristine system or  one that has been flushed out thoroughly cleaned.

Moose

[Cool53]

It really should be pristine, but guys like you and I are going to get it really clean. I flush with fresh water with the block drains open, etc.  I think the radiator and of heater core are the biggest problems. Because most of us are going to do it on our own cars I would flush it and run it several times, until the water comes out as clean as possible. A big thing is to get all the water out. You run this stuff straight, no water at all. I always run a small pressure cap, like a 3-5#, and a coolant recovery system.
The best price I could find us through Lang's Model T Parts.  http://www.modeltford.com in Winchendon, MA. Wait until you lift a jug of it and see how much it weighs.
Running the coolant backwards make a huge improvement, like in a '90's LT1. Can more compression with that, too.