Re: 6 volt to 12 volt conversion with positive ground

Posted by HH56 On 2020/9/14 12:02:16

According to the 38-39 combo shop manual the 38 gauges were most likely Stewart-Warner and the issue you will have with modern senders is none still use the old S-W resistance range which in 38 was probably the same 100 ohms empty, 0 ohms full as was used by other S-W supplied Packard gauges thru 47. Because other brand gauges were also used for other Packard models in those years you might want to verify which brand gauge is in your car since the resistance value may not be the same. Usually but not always the brand name is stamped on the back of the gauge.

If you have the S-W gauges, they are the magnetic type with electromagnet coils so to run on 12v you will need some kind of voltage reducer. For a single gauge the Runtz type regulator is probably the best and much better than an ordinary dropping resistor for keeping the voltage at a known and stable value. If you have kept the positive ground after the conversion then those will not work and you will need to come up with a different plan. Runtz regulators are available from several places including Amazon.

Once the voltage to the gauge is correct the original sender will work if it is in good condition or can be repaired. If you need something custom for your new tank then as far as I know, the only place that might be able to make or supply a sender in the correct resistance range is KM Lifestyle.http://www.mykmlifestyle.com/Packard_Fuel_Sender_0YW2.html

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