Alternator wiring

Magnum Engine Swaps

  1. Will_Swe

    Will_Swe Member

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    Hi everybody!
    I’m in the last stages of my 318 magnum swap, Valiant 1969 originally slant six.

    I’m about to wire up the alternator, but don’t know how to wire it. I want to use the magnum alternator. I have put in a 3 gauge positive cable to battery, but the rest? How do I hook it up properly?

    thx in advance// William from Sweden.
     
  2. fklskv

    fklskv Well-Known Member

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  3. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

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    Easy. The late model alternators have two field wires the same as any other 70/ later Mopar alternator

    If you are using the 70 / later VR, just hook it up as if it was a stock '70 alternator

    If you are using the 69/ earlier VR ground either of the alternator field connections, then hook your green VR wire up to the remaining one.

    These terminals vary. One some they are small stud and nut terminals, and on others they are a proprietary push on factory connector
     
  4. Mattax

    Mattax Just the facts, ma'am FABO Gold Member

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    3 ga is more than enough for the starter. 6 ga was factory.
    The more important wire is the lead from the battery terminal to the starter relay. '69 was either 12 or 10 ga, and I would chose 10 if given the option.

    Now. How to wire the alternator.
    a. I don't know what alternator came on the magnum you have. My guess, and its just a guess, is that its a "revised squareback".
    Post a photo or search for revised squareback to see if the alternator looks the same.
    For a revised squareback, using the voltage regulator that was originally meant for that alternator would be a good idea. It will be able to handle the higher current that rotor can draw. It uses a ground controlling regulator so it needs two changes from a '69 wiring scheme.
    1. The regulator feed must also feed one of the alternator's brush terminals.
    2. The second brush terminal on the alternator must connect to the regulator's second terminal.

    Your factory 69 V charging circuit looks like this.
    upload_2020-8-1_9-33-10.png

    A revised squareback will have a regulator that works like this:
    upload_2020-8-1_9-45-18.png
     
  5. Will_Swe

    Will_Swe Member

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    Thanh you very much! Very helpful! Im gonna check the alternator tomorrow! :)

    I put a 3 gauge from alternator. I have a lot of power consumers, fuel pumps, cooling fans, fuel injection and a total of 2000 WRMS amplifiers.. so i need a good charging system. :)
     
  6. Mattax

    Mattax Just the facts, ma'am FABO Gold Member

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    OK. Yes if there is large draw from the alternator then a large output wire from the alternator makes sense. Although 3 ga is very large I assume you have looked at temperature and load charts or calculators and know all this.
    And I'll also assume that you've changed from the factory wiring strategy to something that will accomadeate high loads on both the battery and the alternator feeds.

    There were other alternators after the revised squareback which I'm not as familiar with. But for those sorts of low rpm loads you might also want to consider a nipodenso (aka Denso). Andy_F was/is making brackets for adapting them to earlier engines.
     
  7. Will_Swe

    Will_Swe Member

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    Yeah, the 3 gauge was large.. But choosed between 3 or 5 gauge at the store, 3 made more sense.

    Rest of system is good, not much of factory wiring left, most was old and needed more modern solutions, also the car had a lot of owners making their own fixes through the years. 22 owners.. Like most cars over here... i ripped out 65 meters of old cable when i bought the car, guess like around 200 feet cables that been put in to "fix" problems... Saved alot of weight there...
    It was once a swedish police car with alot of weird extras..
     
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