fuel sending unit

[324darrin]

I see that there are fuel sending units available for the Henty J and I think they are the same for the Darrin. My Darrin has been converted to 12volts but I have heard that sending units do not care about voltage as they respond to resistance. So my question is whether or not an advertised 6volt unit will work with 12 volts. Steve

[joefrazer]

You are correct, the sending unit does not care about voltage. A sending unit operates on resistance...ohms...so as long as it's compatible with the gauge, you're good to go. Before you use a Henry J unit, I would check the values for each. The HJ unit is ~10 ohms full and ~70 ohms empty. I'm not sure what the Darrin unit should read but I do know that the full size Kaisers used sending units with the same values.

[Corsairdeluxe]

Please reconsider your response as to the voltage. The Fuel gage is a ammeter. The sending unit is a variable resister. The other variable is voltage. double the voltage and you double the amperage.
 The voltage regulator actually limits the voltage applied to the gauges to 5 volts with 6-7.2 voltage input
The voltage regulator is not resigned to function in a 12 volt car. But who knows, it might.

[joefrazer]

The sending unit itself doesn't care about voltage but Corsairdeluxe, you are correct, the dash gauges do. The dash regulator won't last long if 12V is consistently applied. An in-line voltage resister to step the voltage down from 12 to 6 will need to be added. Chrysler used 6V gauges in many of their vehicles up thru at least 1968 and they had a resistor mounted on the firewall to handle the step from 12 to 6. I remember keeping a spare in the glove box because one never knew when it was going to burn out.

[324darrin]

I knew I came to the right place for an answer. Seems like the step down resister is the way to go unless anyone knows of a 12V rated unit that will bolt up to the tank. Thanks, Steve

[Corsairdeluxe]

Disconnect the stock voltage regulator and add one runtz from 12v keyed source to each gauge  . The runtz is not actually a resistor ,but a voltage regulating diode. (FID... see that old time
technology stays with you)

https://www.ebay.com/itm/Voltage-Reducer-12-6-Volt-Runtz-Diode-to-resistor-b/301836332207?epid=1993164216&hash=item4646d8ecaf:g:zZMAAOSwo4pYZfHy

[DTort96646]

Note that the Darrin does not use a voltage regulator for the gauges. The fuel and temp gauges are direct 6 volt key on feed. The resistor would go in the 6 volt key on feed to each gauge.