Temperature Gauge update:
The gauge/sender when fitted, read (with 90 head temp) so close to the H that it was nearly useless.
Attachment:
90 in car.JPG
I sent the gauge back to Howard's, who after three weeks, had not even bothered to get back to me.
I messaged Caerbont (Smiths) in Wales, who got back to me in less than an hour, to say that the sender unit was wrong. They messaged Howards who then sent me the correct TT4806-00 sender for the BT2204-11 gauge. (No apology!!!!!)
It gives a wider spread but I had to fit a 5 ohm resistor (actually two 10 ohm, 1 watt resistors in parallel) between the 7810 voltage regulator (10.14 volts) and the gauge, to move the 82 thermostat point to N on the gauge. The resistor has little effect (about 1%) on the cold readings, but lowers the hot readings by more (about 5%) as the sender resistance drops from 500 (cold) to 37 (at 100 degrees).The white paint marks are 100 degrees; the highest temp that I could calibrate the gauge. When I'm confident that it works perfectly I will fit it into the dash.
Thanks for all the help.
Attachment:
IMG_4860.JPG
I took some IR photos that at least showed that the thermostat is working
Attachment:
IR cool radiator.jpg
Attachment:
IR hot radiator.jpg