The Ford Barn

vern hodgson · 04-08-2015, 12:35 AM

So I have this on my car, looks like what the catalog says is an alternator. Also claims to be neg. ground if six volt. So how do I know if it is neg. or pos.ground? What about the rest of the system, do I connect the battery w/ neg. grind or what?
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Dollar Bill · 04-08-2015, 04:55 AM

If the battery cables are not connected, about the only sure way to identify ground orientation is to remove the alternator and take it to a shop - They will look at the rectifier.

If you're feeling lucky.......

If the coil is correctly wired....negative ground cars have the - side of the coil going to the distributor, Positive ground cars have the + side of the coil going to the distributor.

One other check is to look at the battery cable ends where they clamp to the battery studs. The positive post is larger than the negative.

Tom Wesenberg · 04-08-2015, 05:12 AM

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You can remove the output wire from the alternator, install the battery with positive ground, then connect your test light between the output post and output wire. If the test light lights bright try turning the battery around and use negative ground. When you have the correct ground the test light shouldn't light.

It looks like you have a 28-9 car, but the lower water pipe is for 30-1 Model A's.
Notice the connection at the radiator doesn't line up like it should.

04-08-2015, 04:55 AM	#2
Dollar Bill Senior Member Join Date: Oct 2014 Location: Keystone Heights, FL Posts: 647	Re: Alternator/generator?? If the battery cables are not connected, about the only sure way to identify ground orientation is to remove the alternator and take it to a shop - They will look at the rectifier. If you're feeling lucky....... If the coil is correctly wired....negative ground cars have the - side of the coil going to the distributor, Positive ground cars have the + side of the coil going to the distributor. One other check is to look at the battery cable ends where they clamp to the battery studs. The positive post is larger than the negative. __________________ I Love Anything That Turns Money Into Noise

04-08-2015, 05:12 AM	#3
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: Alternator/generator?? Sponsored Links (Register now to hide all advertisements) You can remove the output wire from the alternator, install the battery with positive ground, then connect your test light between the output post and output wire. If the test light lights bright try turning the battery around and use negative ground. When you have the correct ground the test light shouldn't light. It looks like you have a 28-9 car, but the lower water pipe is for 30-1 Model A's. Notice the connection at the radiator doesn't line up like it should.