charging system blues

Electrical and Ignition

  1. Mattax

    Mattax Just the facts, ma'am FABO Gold Member

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    The other alternator is wired for the earlier style voltage regulator.
    On your '71 voltage regulator:
    Blue wire monitors system voltage. The regulator decides what to do based on this voltage.
    Green wire is the alternator's grounding wire. The Voltage Regulator controls the power flow through the field to ground.

    Voltage regulators before 1970 control the power to the field positive. Field negative goes to casting which is used as a ground.
     
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    • Michael Siple

      Michael Siple FABO Gold Member FABO Gold Member

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      looks like one will not work in the others place - i bought the single pulley thinking the only diff would be a/c or no a/c - have to wait till tomorrow now
       
    • Mattax

      Mattax Just the facts, ma'am FABO Gold Member

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      If you want to bring it by, send me a PM. Put the old alternator back on and we'll figure out what, if anything, is wrong when you bring it here.
       
    • Michael Siple

      Michael Siple FABO Gold Member FABO Gold Member

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      tomorrow i'll take this single pulley back & get what was on it - double pulley with the two fields.
       
    • TrailBeast

      TrailBeast AKA Mopars4us on Youtube

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      There are two alternators, a roundback and a squareback.
      Single or double pulley is for AC and double belt systems like motorhomes or trucks with big fans.
      You have and want a squareback, but with a single pulley, but last I got one they told me they only had 2 pulley because it would work for a car or 2 belt system.
      (Probably BS, but it was all they had around here locally)


      squareroundcomp.jpg
       
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      • Mattax

        Mattax Just the facts, ma'am FABO Gold Member

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        True. For a non-restoration, these generally perform better at low rpm compared to a similarly round-back with the same rating.

        There two styles of alternator housing from the 1960s through the 70s. A point of clarification because this
        is only true if a later alternator was installed.

        The squareback was introduced in 1972.
        http://www.hamtramck-historical.com/images/serviceHighlights/1972/1972 sh p24.jpg &
        http://www.hamtramck-historical.com/images/serviceHighlights/1972/1972 sh p25.jpg

        All 1971 cars originally came with an isolated field round back alternator.
        These were introduced across the 1970 product line. http://www.hamtramck-historical.com/images/serviceHighlights/70 sh 71.jpg
        These are mostly of interest to someone restoring a '70 or '71, especially if it has the correct casting number and date on both halves.

        A pulley swap is relatively easy. Most traditional parts stores will do that for you.
         
      • TrailBeast

        TrailBeast AKA Mopars4us on Youtube

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        I was going on the assumption that he has the square back now and was intending on replacing it with one, because he said he has two field wires on the back of it.
        I was more trying to clarify that the one/two pulleys makes no difference as far as function or type of alternator.

        The places around here won't swap a pulley for you, but they will rent you the tool to do it.
         
      • Mattax

        Mattax Just the facts, ma'am FABO Gold Member

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        Let me come right out and say it. This is wrong. Round back alternators from 1970 throught 1971 had two isolated field terminals and wires connecting to each. Same wiring as used on the squarebacks starting in 1972.
        Please look at the 1970 and '72 Service Highlights (links above) if you have any questions about this.
         
      • TrailBeast

        TrailBeast AKA Mopars4us on Youtube

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        Please do, I ain't delicate like some people.
        Learn something new every day, as they say.:D
        Thank you.
         
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        • Michael Siple

          Michael Siple FABO Gold Member FABO Gold Member

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          here with car now - alt on 1st. cranked up charging @ 13.6-13.8 . good charging voltage anywhere i check with meter. i'll leave the vr alone - its likely better than the one i bought - standard ign vr made in China. on with a remy reman alt -square back dual pulley 60a like i took off. i thank everyone who responded. i have a better understanding of how this particular Duster charges. in time for a couple shows this w/e
           
        • 67Dart273

          67Dart273 FABO Gold Member FABO Gold Member

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          "Here's the thing" about roundback/ squareback.......

          Yes roundback ISOLATED (sometimes called "dual field") were made up until squareback, BUT THE THING IS

          cheap ass rebuilders have "converted" a lot of older GROUNDED field into the 70/ later ISOLATED FIELD and done so INCORRECTLY.

          WORSE, some of these "converted" units "somehow" get GROUNDED BRUSHES installed, AS WELL AS up through "squarebacks" ALSO COMING THROUGH with grounded brushes or broken or missing brush hardware which INCORRECTLY causes one brush to be grounded.

          ALWAYS CHECK that your "isolated field" REALLY IS isolated!!!! Neither brush should be grounded!!!


          Below, on left is one I did not know was made until recently, is it Mopar or aftermarket? If you look closely it has a GROUNDED BRUSH installed, yet it has a spot to mount 2 ISOLATED brushes:

          (On the right is a "regular" squareback)

          [​IMG][/URL]

          this God Damned software!!!!1

          squareroundcomp.jpg

          Below is one of the "junk mexican" rebuilds this is a 69/ EARLIER grounded brush unit that has been "half ass" converted to isolated field:

          At 6 O'clock is the position for the old grounded brush. The "half ass" brush is at 12 O'clock, they just drilled a hole and popped a screw into the case

          20160802_110535-jpg.jpg

          Below is ANOTHER one "you have to watch out for." This APPEARS to be a "normal" squareback WHICH SHOULD BE "isolated field" BUT IT HAS ONE BRUSH GROUNDED

          1851581.jpg
           
          Last edited: Oct 20, 2017
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          • 67Dart273

            67Dart273 FABO Gold Member FABO Gold Member

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            I wish to hell I could get people to NOT do this. It does not really prove anything and can damage electronics including alternator diodes.

            If the engine quits, it MIGHT mean the alternator is simply turning too slow.
             
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