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Old 09-08-2020, 02:07 PM   #1
jquinlan
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Default Reverting back to a positive ground like original

My 28 Truck was modified to have a negative ground. The previous owner told me he did that for his CB. I removed the CB so I'd like to switch it back to a positive ground to be more like original. It has an alternator and I realize I'll have to change that out but not sure about the starter. Are starters wired differently to work with a negative ground? Other than those considerations will I just need to switch the cables on the battery? (there's no LED's in any of the lighting). Thanks
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Old 09-08-2020, 02:20 PM   #2
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Default Re: Reverting back to a positive ground like original

Starter does not care, horn should be good, switch wires on coil so + side is toward the points (ground), may have to switch wires on ammeter.
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Old 09-08-2020, 02:22 PM   #3
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Default Re: Reverting back to a positive ground like original

Starters don't care on polarity ! Change the wires on the coil, that's about all I can think of?
But why change if every works, nobody will see the change!
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Old 09-08-2020, 02:45 PM   #4
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Default Re: Reverting back to a positive ground like original

Are you changing voltage ? Are you going back to a generator ?
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Old 09-08-2020, 02:52 PM   #5
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Default Re: Reverting back to a positive ground like original

Thanks for the feedback. Much appreciated. I'm glad that I won't need to change the starter.

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Starters don't care on polarity ! Change the wires on the coil, that's about all I can think of?
But why change if every works, nobody will see the change!
I have another Model A and another engine on a stand that are both wired correctly so I just want consistency. I know nobody will know but I will : )
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Old 09-08-2020, 02:54 PM   #6
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Default Re: Reverting back to a positive ground like original

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Are you changing voltage ? Are you going back to a generator ?
No, I'm going to stick with an alternator but I will stay with 6 volts. He ran an inverter to jump to 12 volts with his CB.
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Old 09-08-2020, 03:53 PM   #7
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Default Re: Reverting back to a positive ground like original

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Originally Posted by jquinlan View Post
Thanks for the feedback. Much appreciated. I'm glad that I won't need to change the starter.



I have another Model A and another engine on a stand that are both wired correctly so I just want consistency. I know nobody will know but I will : )

I can see where consistency is a plus when you have multiple cars. That keeps you from having to remember which car is wired “backwards.”

In my line of work (Database Administration), we try to make sure everything is configured the same and fails the same. That way, the same fix should work in multiple places. Life is just simpler that way. ;-)


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Old 09-08-2020, 06:16 PM   #8
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Default Re: Reverting back to a positive ground like original

OK, stupid question, why would one need to switch polarity to run a CB? (or anything else). Just put the positive wire for the CB to "ground" which is the positive side of the battery and the negative to where ever you want to get "power" from the negative side of the battery. What am I missing???
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Old 09-08-2020, 06:24 PM   #9
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Default Re: Reverting back to a positive ground like original

post a picture of the back of the alternator, some can have the polarity changed on the outside
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Old 09-08-2020, 07:56 PM   #10
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Default Re: Reverting back to a positive ground like original

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Originally Posted by Licensed to kill View Post
OK, stupid question, why would one need to switch polarity to run a CB? (or anything else). Just put the positive wire for the CB to "ground" which is the positive side of the battery and the negative to where ever you want to get "power" from the negative side of the battery. What am I missing???
Only reason I can think of is if the chassis of the CB is negative (ground) then you could not install it in a positive ground car unless you mounted the CB so it was completely isolated from the car. OR change the car polarity to negative ground.
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Old 09-08-2020, 08:06 PM   #11
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Default Re: Reverting back to a positive ground like original

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Originally Posted by Licensed to kill View Post
OK, stupid question, why would one need to switch polarity to run a CB? (or anything else). Just put the positive wire for the CB to "ground" which is the positive side of the battery and the negative to where ever you want to get "power" from the negative side of the battery. What am I missing???
That's what I was told but you got me wondering so I did some searching on the internet and did see how you will damage diodes by reversing polarity with older CB's. Not my area of expertise for sure.
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Old 09-08-2020, 08:09 PM   #12
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Default Re: Reverting back to a positive ground like original

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post a picture of the back of the alternator, some can have the polarity changed on the outside
I attached a picture of the alternator I currently have. Noticed another area for a threaded bolt on the other side of the alternator. That would be nice if I could continue to use the alternator I have. Thanks
Attached Images
File Type: jpg IMG_8925.jpg (24.8 KB, 35 views)
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Old 09-08-2020, 08:35 PM   #13
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Default Re: Reverting back to a positive ground like original

That is a Delco 10SI alternator. You will need to change the rectifier to a positive ground unit and the way it is wired.

https://www.ebay.com/itm/10SI-Delco-...-/190696606664
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Old 09-09-2020, 08:22 AM   #14
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Default Re: Reverting back to a positive ground like original

Just the rectifier unless you think you need the whole kit - but you will also need the jumper wire and screw insulators

https://www.ebay.com/itm/10SI-Delco-...YAAOSwQqNcVvcN

Swap posts on battery, coil and ammeter to change grounding.
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Old 09-09-2020, 09:34 AM   #15
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Default Re: Reverting back to a positive ground like original

Thanks again all, very helpful and appreciated.
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