The Ford Barn

rotorwrench · 04-21-2026, 06:47 PM

The big unknown is what Ohm range would give a King Seeley quantity indicator a full sweep from E to F. The current pulse system didn't have the same range due to the way it controlled power at the indicator. The indicator function is the same theory but current control doesn't involve any rheostat. The float arm movement affected the movement of the sender breaker points on the bi-metallic regulator switch arm. K-S used a resistance wire spool and a carbon resistor to calibrate the system circuit. If you chuck the original sender and convert it to rheostat, the Ohm difference between E and F on the indicator need to match up with the resistance range that gets it there.

Ohm controlled quantity systems use specific Ohm values and from research, most are limited to three or four different values between different manufacturers. They should test a K-S indicator with a good variable resistor test aperatus to find what range effects it and manufacturer one that works. I think they just got one of the off the shelf units that's close and called it good. I'd be surprised if they care whether it works or not.

04-21-2026, 06:47 PM	#13
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 18,012	Re: grounding bob drake fuel sending unit The big unknown is what Ohm range would give a King Seeley quantity indicator a full sweep from E to F. The current pulse system didn't have the same range due to the way it controlled power at the indicator. The indicator function is the same theory but current control doesn't involve any rheostat. The float arm movement affected the movement of the sender breaker points on the bi-metallic regulator switch arm. K-S used a resistance wire spool and a carbon resistor to calibrate the system circuit. If you chuck the original sender and convert it to rheostat, the Ohm difference between E and F on the indicator need to match up with the resistance range that gets it there. Ohm controlled quantity systems use specific Ohm values and from research, most are limited to three or four different values between different manufacturers. They should test a K-S indicator with a good variable resistor test aperatus to find what range effects it and manufacturer one that works. I think they just got one of the off the shelf units that's close and called it good. I'd be surprised if they care whether it works or not.