Does anyone know which is the correct resistor to use to make a 6 volt '40 Ford fuel gauge work with 12 volts? There is currently a Runtz device in there which has failed twice in five years so now I would just like to use the appropriate resistor. Thank you.
i use a intrument voltage regulator from 60's fords i believe the napa p/n is ir-1 or vr-1. kinda pricey but works great.dont waste your time dickin with resistors...
If you want to be absolutely sure, give a call to Bob's Speedometer in Michigan. They're the masters of instrument restoration - I was amazed at what they did for my cluster, and they'll certainly know what to tell you. Do a Google search, they're easy to find.
We prefer to build our own solid state voltage reducer to run each gauge. The simple physics of a resistor cause the amount of current, flowing through the gauge, to change as the variable resistance from the sender changes. Originally, your vehicle had a thermal points actuated sending unit that regulated the average voltage through the gauge (less than 6 volts) by the opening and closing of points in the sender. This pulsing rate changes with the level of fuel and can cause problems with inferior voltage regulators as well as resistors, due to the surges of current. A modern "rheostat" style sender and a modern voltage regulator is usually the route we go, unless the original senders are needed for cosmetic reasons.
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