I am converting my 54 F100 electrical system to 12 volts using a 56 generator, etc. The 54 was a positive ground system. Are the 12 volt systems negative ground? If so, what will happen to my guages when I convert to the 12 volt system? Will they read backwards? How can I fix the problem?

thanks

 

Moved to Electrical Systems/Wiring forum

 

They won't read backwards. They would if they had a permanent magnet inside the movement where the north/south poles are fixed. But they usually have another coil that will change polarity in conjunction with the movement coil when the polarity is changed, just like the starter. You can use the 6 volt positive ground starter in your new system. Some of Ford's guages even work on heat and a bi-metal spring. I can't remember what they use in 54, but you will be ok as far as polarity.

You do need to step the voltage down to 6 volts though for the original guages. JCWhitney sells little reducers that bolt right to the guages themselves.

Of course you will be replacing all your light bulbs to 12 volts.

You need to step down your heater fan motor somehow. I retro-fitted a 12 volt fan out of a later car into my original 53 f100 heater box.

The biggest problem I had was the wiper motor. I used a resistor to step the voltage down, and this does not work good at all. When the windshield gets dry, the motor draws more current, so the resistor drops more voltage, and the wipers get really weak. When the windshield gets wet, the motor draws less current so it runs way too fast. It will run so fast, it will coast by the park switch and they keep running with the switch off. Find another motor or a regulated step down convertor. I can't remember if a 56 motor will fit or not?