Today I removed the tape from the sending unit. I grounded the wire and the gauge needle went all the way past hot. I hooked it back up and went for a ride. As yesterday I got my typical cold reading and after 10-15 minutes the needle swung quickly to full hot. Not believing it, I drove another 20 minutes at full hot on gauge. Immediately after parking I stuck a thermometer in the radiator and got just over 170. I ordered my sending unit from truckandcarshop.com for a '56-'58 V-8. My '58 has a 283 V-8. That was an interesting point about the wire which may be against the intake manifold but I never got anything above a cold reading before yesterday when I changed the old sending unit. So, I have a new wire, new sending unit, new 180 degree thermostat and a radiator that was flushed two months ago and a 48 year old gauge and I'm still not sure what's the problem. Maybe I need to get an ohmeter to check the sending unit as suggested. Scratching my head.
