Edited: another fuel/temp gauge thread, but turns out the harness is melted together

hotrod swinger said
Almost entirely cooled: 110
Normal operating temperature: 24

So the gage should have read near the middle whe nthe engine was hot. Right?
And the cold end of the scale will be off.

hotrod swinger said
I replaced my fuel sending unit a few years ago, and with an aftermarket gauge it read full when full and ready empty with 12 litres of fuel in the tank. With my stock gauge it reads full when full and empty with 40 litres in the tank.

They've got to be matched units. Plus the float arm and its resistance need to be calibrated for the arc and the tank shape.