Heat Temp Sensor?

[Richard Dobson]

I got my 396 engine started a let it run for approx 15 minutes with no movement on the temperature gage. I have put in a new 180 deg thermostat, new alum water pump, new hoses. I have a 4 core rad. Have I let the engine run long enough? The hoses were hot, the rad was hot, so I was concerned when the temp gage showed no movement at all and shut the eng off. I ran a wire from the temp sending unit to a bolt on the intake and had the wife watch the temp gage and it pegged out to the hot position. Does this mean the sending unit is bad? Thanks for all replies.