Can use some Thermostat and Rad Cap advice

If the state is 160 deg it is fully open at 200 and has been for 40 deg.
Naw. That ain't how it works. The thermostat doesn't magically pop open at the specified temp. It BEGINS to open. It MIGHT be completely open in ten degrees. Might not. But the specified temp of the thermostat is where it begins to open.