Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks



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Joined: Jan 2014
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Camile Offline OP
Shade Tree Mechanic
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Shade Tree Mechanic
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I have a 38 pickup and it has been converted over to a 12 volt system because it has a fan for the radiator. I have a separate gauge cluster for temp, oil pressure and voltage. But I still have some original gauges and I'm not having any luck getting the fuel gauge to work. Has anyone had success with using the original type 6 volt gauges with a voltage reducer in a 12 volt system?

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ChatMaster - 6,000
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ChatMaster - 6,000
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Camile
I cannot see any issues with your idea though I have never tried it. While the voltage remains under 7 and definitely under 7.5 all of the original equipment will be happy.
Tony


1938 1/2 ton Hope to drive it before I retire
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ChatMaster - 1,000
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Google search Runtz resistor. One is needed for the gas gauge and each 6 volt accessory.

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ChatMaster - 2,000
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For the gas gauge, a 30 ohm 2 watt resistor should work just fine. The gauge is easy to test.


My 1951 1 Ton is now on the road! My 38 Master 4 Door is also now on the road .
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HCB Offline
Grease Monkey
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Any suggestions for a good step down from 12 volt to a 6 volt heater motor in my 1955 1st Series pickup? I tried a regular one and it heated up badly. Or should I just swap out the 6 volt heater motor for a 12 volt?

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ChatMaster - 1,000
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If the gas guage was not addressed when it was converted to 12 volt, it is probably burned out.


1946 Chevy 3100 1/2 Ton Pickup Purchased 11/18/17 Sold 9/20
1948 Chevy Fleetmaster Coupe, Purchased 6/20/2010
1965 Chevy ll 350 Purchased Feb 2021. 3-speed Saginaw Hurst Floor Shifter 3.08 Rear End

2019 Ford Ranger Lariat Super Crew
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Lou Offline
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The fuel gauge works on varible resistance. You will never get an accurate reading with a resistor voltage drop. You could also burn out the gauge and sending unit and possibly explode the tank.
If you spend 63 cents for a 7806 voltage regulator from digikey.com, you will have a constant 6 volts negative ground to the gauge.
For details, please check out my webpage: <http://home.znet.com/r1937/Fuel.htm>.
Good luck, Lou

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Hall Monitor
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FWIW and to add a bit of mud to the water I'll tell you about my experience with this very issue. As a strapping lad in my early 20s I bought a 55.1 Chevy panel truck. It was 6v. I converted it to 12v. In doing so I replaced the battery/coil and light bulbs. In my ignorance I put no resistors on anything. I put over 100K miles on the truck with no electrical issues whatever following the conversion. Having said that I'm not recommending you do the same thing. I may have just been lucky. My point is that the assertion that you'll fry everything unless you put resistors on them may not hold true in all cases.


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1938 HB Business Coupe
1953 210 Sedan
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ChatMaster - 2,000
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A while ago I did a little research on my bench with a 38 Master gas gauge sender and gauge. I found that I could vary the voltage quite a bit without affecting the reading much. I used my variable voltage supply to do this. Many folks use a resistor for the gauge feed with great success.


My 1951 1 Ton is now on the road! My 38 Master 4 Door is also now on the road .
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A 6 v. system converterted to 12 will burn your gas gauge out.. My 54 suffered that twice,, standing on your head to replace that gauge is a bear.. Use a resistor...Ps probably your radio too..All bulbs..headliner bulb.. dash lites..Patricks..Casa Grande Az. has a great reference sheet


Old cars have always owned me.

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