I have been experiencing some 220+ temperatures in very cool spring weather, and thought that was odd. I took some advice from in here, and used a heat measuring tool and never got a reading over 198, on the side of the radiator, nor the thermostat housing. My guess is the guage is out of calibration. The whole time i have been able to hold on the upper rad hose, if it were 220+, i wouldnt think that could be possible. Everything else is new and cleaned out properly. I am going to try some other "used" guages, pretty soon to verify it.

 

There is no way you could hold on to the upper hose without getting serious burns if it was 220. Sounds like the gauge is out of wack. It may not be the gauge though, could be the sender. Check the resistance.

 

The cooling sending unit is new, and i thought i ruled that out. But after thinking about it, and reading some other posts, i am going to relocate the sending unit to the stat housing and not use the one in the drivers side head. I may be getting hot spot readings from the head water, and the guage may be accurate after all. I think the sending unit in the stat housing will show the most accurate water temp in relation to the thermostat that i have installed. Will post results this weekend.

 

Check the heater core. I had the same problem with an 89 Blazer with a 350. Radiator was re-cored, new thermostat, but gauge would be pegged after quater of a mile. Radiator wasn't hot and the hoses felt cool to the touch.
Turns out, the heater core was plugged. Hope that helps.