As Rusty said above, you radiator is junk. 4 cores is the first problem. You need a 2 core with at least a 1.000 tube.
Then you need a high flow water pump. If you already have that, that’s good. I may have missed it.
I know Evans is big on not running a thermostat, but if the rest of the system is correct, you’ll have to run one to get some heat in the engine. As PRH posted, the Stewart Components is about the best there is. A 180 degree thermostat is plenty hot.
Next on the list is pump speed. You need, at the very minimum, the water pump turning crank speed. That is 1:1 at the very minimum. If you can get the water pump turning 10% or 15% faster than crank speed you’ll be much better off.
Leave the Evans coolant in there. It’s not the problem. The wrong radiator, and getting the pump speed where is should be will fix 99% of your issues.
