Its in exactly the stock spot where the factory sender was. Right behind the thermostat in the top of the head. The wire is a new 12v 12gauge wire that goes from the sender, behindthe alternator, across to the fender and up to the ffirewall harnessed with the ignition, tach, etc. Just like factory one was. I even used the factory wire for a while but assumed that wire was messed up somehow - both gauges did not function with the old wire.

I am getting a third one. I found a deal on a Chrysler six cyl tach, temp gauge and some other stuff. Well see what it does.

Its in exactly the stock spot where the factory sender was. Right behind the thermostat in the top of the head. The wire is a new 12v 12gauge wire that goes from the sender, behindthe alternator, across to the fender and up to the ffirewall harnessed with the ignition, tach, etc. Just like factory one was. I even used the factory wire for a while but assumed that wire was messed up somehow - both gauges did not function with the old wire.

I am getting a third one. I found a deal on a Chrysler six cyl tach, temp gauge and some other stuff. Well see what it does.

I'm not an expert in instrument repair but I think you may have a bad instrument panel regulator or a bad circuit board. Dashboard instruments are supplied with 5V from a mechanical regulator. Replacement regulators are still available but you can also upgrade to an electronic regulator. A broken trace on the circuit board can be repaired with solder and nail polish.
http://www.allpar.com/history/mopar/electrical2.html
http://www.feep.org/weblogs/josh/archiv ... panel.html
You could get scalded opening the rad cap of a hot engine - don't do that again. I would just let the engine warm up in the driveway with the cap off. When you first see coolant movement, your thermostat is starting to open. You can make the engine run hotter by covering part or all of the rad.
I don't think you would see very much flow in the rad tank from 3 very small holes in the thermostat. I get zero flow through my thermostat (Stant SuperStat) with a cold engine.

Starting with a cold engine, watch the flow in the rad. The thermostat should be completely closed, which would result in a negligible flow to the rad. If you can see movement, your thermostat is not closing properly.

You can double-check the accuracy of your meat thermometer by putting it in boiling water on the stove. Since you're very close to sea-level, the water temperature at a rolling boil in the pot should be exactly 212°F. If there's an adjusting screw on the back of your gauge, you can use this to calibrate the gauge.

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1965 Plymouth Barracuda,
225 engine, Quadrajet, HEI, Dutra Duals, 904 Torqueflite, 2.76:1 axle, Addco front bar
Rods & Relics - Fort Erie, ON / Collector Car Tech