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Old 12-02-2019, 10:34 AM   #1
Flyboy1st
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Default Alternator Replacement 12V

What 12 volt alternator will replace my 6 volt Newrex alternator. I just want to go to my local parts store and get 12 volt replacement that will use the brackets and pulley that I received from my Newrex alternator kit.
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Old 12-02-2019, 10:52 AM   #2
Charlie Stephens
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Default Re: Alternator Replacement 12V

Are you positive or negative ground?

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Old 12-02-2019, 12:31 PM   #3
Purdy Swoft
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Default Re: Alternator Replacement 12V

The twelve volt alternators that I've seen advertised in the model A parts catalogs are negative ground .
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Old 12-02-2019, 12:59 PM   #4
mleder
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Default Re: Alternator Replacement 12V

The grounding issue if going 12 volt and you want an off the shelf unit will have to be changed. The physical size is a Delco 10 S I This GM alternator was used on cars from the 60's and 70's are used most often.You will also need to change your light bulbs and I believe the coil or add a resistor. (this you may want to look further into. From just about any local shop rebuilder they can change the ground if you want and also the voltage.
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Old 12-02-2019, 01:07 PM   #5
Kurt in NJ
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Default Re: Alternator Replacement 12V

Most likely your "nu- Rex" can be converted to 12v by changing the regulator
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Old 12-02-2019, 01:30 PM   #6
30 Closed Cab PU
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Default Re: Alternator Replacement 12V

Do a search here on the subject, anything electrical needs to be considered when converting from 6 to 12v. Horn, starter, bulbs, coil, etc. If switching from positive to neg ground - coil wiring, possible reversing leads at the ammeter repolarizing the gen. May be other possibilities. Should have been discussed in depth already on FB.
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Old 12-03-2019, 03:39 AM   #7
Mike V. Florida
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Default Re: Alternator Replacement 12V

http://www.madelectrical.com/electri...reewire2.shtml
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Old 12-03-2019, 05:35 AM   #8
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Default Re: Alternator Replacement 12V

I run a regular 12 volt 1-wire Delco alternator, can get them at any parts store. My is is converted to negative ground which meant a 12 volt coil and switch some wires due to polarity change. I converted my starter to 12 volts (6 volt starter will work but will take it's toll on starer drives if you dont convert to 12. Car runs better and significant improvement in lights (bulbs also need to be converted to 12 volt) Additionally you will need to change out the pulley on your alternator (take the on e off your old alternator). I have been running this setup for several years. Battery has tons of reserve now, don't really worry about it running down during cranking. Also put a resistor in your horn.


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Old 12-03-2019, 09:46 AM   #9
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Default Re: Alternator Replacement 12V

Just remember if you do go to the 1 wire alternator, to pull the fuse if you have one or turn off the disconnect switch as there is a small parasitic discharge with this type alternator. It will eventually discharge your battery. Also have to rev the engine to get the alternator to start putting out. You can make a small change by adding a diode and converting to three wire alternator set up to prevent this.
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Old 12-03-2019, 12:13 PM   #10
katy
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Default Re: Alternator Replacement 12V

Quote:
Originally Posted by Flyboy1st View Post
What 12 volt alternator will replace my 6 volt Newrex alternator. I just want to go to my local parts store and get 12 volt replacement that will use the brackets and pulley that I received from my Newrex alternator kit.
Why not take your existing alternator to your local parts store and ask them?
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Old 12-03-2019, 02:18 PM   #11
Purdy Swoft
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Default Re: Alternator Replacement 12V

The twelve volt one wire alternators offered by model A parts venders is probably less expensive than the ones offered locally . Years ago it was mentioned that NAPA offers some model A distributor parts and possibly other model A parts . Being as there was a NAPA store just across the street from my body shop , I went in and ordered several distributor parts just to keep in stock . I was sort of surprised how much more that the parts from NAPA cost than the parts from Brattons or Snyders . Even though I didn't need to pay shipping the prices were way more expensive . I learned a lesson , thank goodness that it didn't break me !!!
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Old 12-03-2019, 04:55 PM   #12
duke36
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Default Re: Alternator Replacement 12V

Try Wagner Products Company; 6 and 12 volt 1 wire alternators for Model A's.
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Old 12-04-2019, 05:59 PM   #13
jrelliott
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Default Re: Alternator Replacement 12V

Conversion kit for GM 10SI and 12SI altenators to 1 wire
Quick Start SE-590

An alternative to the Single wire altenators which require revving the engine to get to charging, You can get a DA plug from NAPA or other vendor. Take the red wire on the DA plug which attaches to the F terminal on the alternator and attach a ring terminal to fit the HOT wire from the Alternator. On the second wire from the DA Plug (usually white in color) which goes to the R terminal on the alternator attach a moderate 3A/ 100V diode cathode side to the white wire from the DA plug. Attach several feet of wire to the anode (other end of the diode) and wire this to the coil (hot side) on your Model A. Cover the diode with heat-shrink tubing to prevent a short before attaching to the coil. Do not skip this step or use cheap tape. The diode is required or engine will not turn off. This set up is very inexpensive and will work on the single wire altenators also. What is nice about this modification is that you can get a replacement alternator anywhere and only have to change the pulley and you are ready to go. Have made this modification to several cars. Must put a fuse in system or battery will run down due to current being fed to fields of alternator when key off on Model A. Pull the fuse when
not running the car.
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Old 12-05-2019, 08:19 AM   #14
Flyboy1st
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Default Re: Alternator Replacement 12V

Negative ground
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Old 12-05-2019, 09:57 AM   #15
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Default Re: Alternator Replacement 12V

Thanks, jrelliott. I had heard this could be done. I find there are a couple places you can buy it premade -

https://www.speedwaymotors.com/Speed...xoCgREQAvD_BwE
https://www.just8ns.com/DI1000-Years...hoCJW0QAvD_BwE

Doesn't do me much good as my alt is 6V positive ground, and speedway says not for one-wire anyway.

Last edited by Badpuppy; 12-05-2019 at 10:04 AM.
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