New sending unit, a stainless steel aftermarket appears to be reading accurately. I think this is unusual for the aftermarket units, is it not?
The OEM ones needed "tweaking" sometimes.
I remember working at the dealer in the late 60's, early 70's and there was a chart that showed the resistance from full to empty. If you wanted it to be spot on you measured the resistance of the sending unit full sweep from full to empty. Usually 10-73 ohms. You then picked the resistance for 1/2 a tank and we had a tool that you could set the resistance with (nicknamed the "dial a prayer") . You connect that to the wire connector at the sending unit and check the gauge. If it wasn't exactly on 1/2 you could pull the instrument cluster out and adjust it through the little holes on the back of the gauge using a small screw driver. Didn't do it a lot but occasionally we had to do it to satisfy a customer
I have some extra nice original tank senders restored by desert classic if anybody needs an assembly line dated original call me.
Quote from: Steve McDonald Formally known as Mcdonas on November 06, 2026, 07:31:40 AMThe OEM ones needed "tweaking" sometimes.
I remember working at the dealer in the late 60's, early 70's and there was a chart that showed the resistance from full to empty. If you wanted it to be spot on you measured the resistance of the sending unit full sweep from full to empty. Usually 10-73 ohms. You then picked the resistance for 1/2 a tank and we had a tool that you could set the resistance with (nicknamed the "dial a prayer") . You connect that to the wire connector at the sending unit and check the gauge. If it wasn't exactly on 1/2 you could pull the instrument cluster out and adjust it through the little holes on the back of the gauge using a small screw driver. Didn't do it a lot but occasionally we had to do it to satisfy a customer
That is an interesting methodology I was unaware of. Thank you for the information.