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12v pos. ground to 12v neg. ground


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ok. i have did some slight research and looked for a thread but i havent founf anything that gives me the right answer.


i am converting my 320 from a 12v positive ground to a 12v negative ground.


i have did my homework but i cant figure out which alternator to get and or how to set it up.


based on that, not only with recomendation but any part #'s for which alternator to buy.


i have heard i should get a one wire / internally regulated because of the simplicity.


then there is the wiring. i got these from 510realm.com or something like that for the KA system. is this how i should set it up.










i will be honest, if i can avoid the voltage regulator i would but if i need one then i will do the same.


please let me know. i am lost.

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Generally, any alternator is going to be negative ground. Just putting that on, will switch the polarity. I did this switch on an old tractor that was 6 volt positive ground, it is now 12 volt negative ground.


The GM "one wire" alternator needs to have the idiot light hooked up, or is does not charge until the engine is revved a little. so technically, it is a two wire hook up. On my tractor, I did not bother to do this, and when I start the tractor, is starts without the alternator charging until I rev the engine.


Obviously, you have to switch battery polarity.


The starter may, or may not be an issue. Take the starter out, and hook it up to a battery, with the starter frame hooked up to the positive battery post, and see what way the starter turns. Then switch the polarity on the starter, and see if it turns the same way.


All the lights do not care what polarity they are.


The heater fan motor may have to have the two wires switched on it, to make it work better.


The windshield wiper motor may run backwards, but that should be OK, it just turns a short crank that moves the wipers back and forth, and it should not be a problem.


The engine may run a little better if you switch the side of the ignition coil the two primary wires are hooked to.

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Not all GM alternators need the idiot light. The ones that are made for tractors have a little shunt that goes where the plug is, to eliminate it. Of course, having the shunt means you can't hook up the alternator wire. I ran one in my Citation for a while, since the 1-wire was cheaper than the "proper" alternator.


My 320 came with a plain GM 27si alternator. No external regulator needed. Worked fine. About the only thing that worked, actually.



I've been told the starter should be good to go, but I tend to be skeptical. I have a degree in Electrical engineering, and I know there are electrical motors that turn the same way irregardless of polarity, but I'm not convinced a starter is one of them. However, it's not a permanent-magnet motor so it likely will work either way. If it works you'll know right away. If it doesn't you'll need to use the starter from a J13-equipped 520, which is the closest "normal" starter.

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Newer starters with a permanent magnet field are polarity sensitive. Old starters use electromagnets in the field. When you hook up one of the old starters to reverse polarity, it reverses the magnetic polarity on both the field windings, and the armature of the starter. In this case, two wrongs do make a right.

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Years back i met the owner of a 65 L 320 & he was running a alt. out of a newer vehicle. Not sure if this meant his truck was then negative ground but im almost positive that he did this mod to eliminate the voltage regulator. Somewhere in 1 of my Photobucket acct's i have a pic of the plug on the back of the alt that may help you. Lemme know if you need it.

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Hi there Burrito, this is the alt. that mike put in my NL320, I don't know what it is out of. Maybe someone will recognize it while reading this thread.:unsure:



Maybe you could/should contact mike and pick his brain, but it has been so long he might not remember anymore, but can it hurt to try. He changed mine over to 12V neg ground. :D wayno

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Laecaon, you have better eyes than I do, I would have to pull it off to find out if the tag is still there, I went out and looked, gave up, and went to mikes NL thread and found these oics. on like page 10,:blink: thats after i found the thread on page 11.:lol: :lol: :lol: :lol: Mike does not say what the alt. is from in the thread. :( Maybe I can use a mirror when it is light out. :unsure: In the end I will find out what it is. :D wayno

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Hey Burrito, if the alt. is good, use it. Then after everything works, and if it is still driving you crazy, replace it with a new one. That alt. on my truck is a used one, mike put on, then continued to the next thing that needed fixed, he made a electronic dizzy out of two used distributers. wayno

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Hey Burrito, if the alt. is good, use it. Then after everything works, and if it is still driving you crazy, replace it with a new one. That alt. on my truck is a used one, mike put on, then continued to the next thing that needed fixed, he made a electronic dizzy out of two used distributers. wayno



how do you check to see if it works?.... is it as simple as, put it all together and se if it holds a charge?....


as far as dizzy, i am pulling my hair with this one because i started a thread but i really didnt get solid answers. basically i didnt know exactly which EI dizzy to get to use for the 1 non EI + 1 EI = 1 EI thats moded.

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  • 2 years later...

Burrito, Thanks for putting together this thread. It is the best one I have found so far regarding converting. Did you every finish the job? Any advice? I need to get this done. 




hi Thomascain - you know, i see these dates and it is technically a time stamp from the last time i had 100% motivation on my truck. time passed, finances dwindled, and interest became limited... i have bought a lot of parts since then but have not any updates as far as wiring and install. but the motivation is coming back. just need time now.


i did however buy a new Alt. and had to fabricate parts from a bracket from a billet chevy bracket kit i bought off ebay. i had to buy a bigger belt from Napa auto but so far it looks good too. i have a pic but will have to dig it up.


thanks for bumping this thread. i will add it to my archive and update it when i make the full conversion.

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