The Ford Barn

Jim/GA · 06-16-2024, 02:06 PM

Any car that has been stored for 40 years will still be 6 volts.

The post size is a good clue. I suspect positive ground. Most people were happy to leave the cars positive ground 40 years ago, there was no incentive to reverse it.

Hooking it up backwards from how it is intended to be will reverse the polarity on the coil, which will give a weak spark. The engine will start, but you will want to confirm the polarity of the coil. The starter, the bulbs, even the generator will not care about the ground.

I recently worked on a car with the coil polarity reversed. The plugs were fouled. The owner was complaining of lack of power (which it should not have been -- the engine was a fresh rebuild with HC head).

06-16-2024, 02:06 PM	#8
Jim/GA Senior Member Join Date: May 2010 Location: Young Harris, GA Posts: 2,094	Re: Can’t determine battery ground Any car that has been stored for 40 years will still be 6 volts. The post size is a good clue. I suspect positive ground. Most people were happy to leave the cars positive ground 40 years ago, there was no incentive to reverse it. Hooking it up backwards from how it is intended to be will reverse the polarity on the coil, which will give a weak spark. The engine will start, but you will want to confirm the polarity of the coil. The starter, the bulbs, even the generator will not care about the ground. I recently worked on a car with the coil polarity reversed. The plugs were fouled. The owner was complaining of lack of power (which it should not have been -- the engine was a fresh rebuild with HC head). __________________ Jim Cannon Former MAFCA Technical Director "Have a Model A day!"