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6 volt positive ground wiring question

Discussion in 'The Hokey Ass Message Board' started by Minncat31, Jul 16, 2010.

  1. Minncat31
    Joined: Feb 7, 2010
    Posts: 13

    from Duluth

    Well, first off I am new to this forum so I better introduce myself. My name is Adam and I am tackling my first car project, a 1950 mercury 4 door. My question I have is that when I hook up the 6 volt battery (positive ground) the starter just spins over but the car won't start. I reversed the pos/ground cables and the car would start, although the starter turns over very slow. Any input would be appreciated. Thanks, Adam

    ps. My loggin minncat was a carry over from a caterpillar site. I had a few 1930's cats but my wife and kids didn't care for them all that much! I'm looking forward to including the family on the car restoration. They think it's pretty cool.
  2. are you sure you have the ground identified correctly? 6 volt systems crank very slowly compared to 12 volt, this is normal.
  3. Minncat31
    Joined: Feb 7, 2010
    Posts: 13

    from Duluth

    I followed the negative cable to a bolt on the motor. The positve cable goes to the starter relay? When I run pos/pos, neg/neg the starter turns slow like it should and the car runs.....That's where I'm stumped.
  4. jamesgr81
    Joined: Feb 3, 2008
    Posts: 261


    Don't you mean you followed the positive cable to a bolt on the motor....

    If it's positive ground?
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  5. ArtGeco
    Joined: Apr 6, 2005
    Posts: 754

    from Miami

    Your description leads me to believe it's Negative ground (grounding to block) lists it as + ground. I'm stumped.
  6. shinysideup
    Joined: Sep 1, 2008
    Posts: 1,627

    from ruskin, fl

    Its wired NEG ground from your desciption.
  7. butcherted
    Joined: Oct 17, 2006
    Posts: 763

    from hagerstown

    <meta http-equiv="Content-Type" content="text/html; charset=utf-8"><meta name="ProgId" content="Word.Document"><meta name="Generator" content="Microsoft Word 9"><meta name="Originator" content="Microsoft Word 9"><link rel="File-List" href="file:///C:/DOCUME%7E1/Ted/LOCALS%7E1/Temp/msoclip1/01/clip_filelist.xml"><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:DoNotOptimizeForBrowser/> </w:WordDocument> </xml><![endif]--><style> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0in; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> </style> Check your points and voltage regulator to see if the point is stuck. I have seen this happen if the battery is hooked up wrong or some body tried to start it with a 12 V battery.
  8. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,648


    The car was originally a 6V positive ground. Many have been swapped over the years and sometimes "force of habit" causes people to install the battery backwards. Yes, 6V starters spin slowly, but that's OK.

    Actually, both the starter and the coil should work with polarity either way and the engine should crank and start. The coil will work better when the coil is "aligned" with the correct polarity to the battery, but it should at least generate enough to spark even if it's not. In other words, when positively grounded, the coil "+" side should go to the distributor and vice-versa when negatively grounded.

    Does your car have an alternator or a generator? Generators have to be polarized (search threads here) to the battery polarity. I believe alternators can only be negatively grounded.

    Your ammeter also has to be wired correctly. You'll see that a heavy wire passes through a metal loop in the back of the meter. The direction the wire passes has to be reversed depending on polarity. If you see the meter run backwards (showing discharge when charging, etc.) then disconnect the wire at the source, unfeed it, and refeed it the opposite direction (right to left, left to right).
  9. tommy
    Joined: Mar 3, 2001
    Posts: 14,763

    Member Emeritus

    Your Mercury came from the factory as a positive ground system. The positive battery connection goes to the block. Were the cables hooked up to a battery when you got it or did you decide which cables were positive and negative when you hooked them up?

    BUT that has nothing to do with your problem. If the starter motor is turning over but the engine is not turning over then you have a problem with the starter bendix most likely.

    When the starter turns over centrifugal force throws the bedix and it meshes with the flywheel turning over the engine. Something is prventing them from meshing. Pull the starter and check out the bendix with the gear on it. You should be able to test it on the bench with simple jumper cables. Just be careful, the bolts that hold the starter on the engine also hold the starter motor together. Put some nuts on those bolts before you test it on the bench.
  10. Minncat31
    Joined: Feb 7, 2010
    Posts: 13

    from Duluth

    Thanks to everyone for all your input. I'm leaning towards the conclusion that the car was switched to negative ground at some point. It started right off today and I took it for a ten mile drive. However, I'm going to take the car to a freinds auto electric shop and have him go through the charging system for me. The car does have a generator and the guage reads that it is charging but I'd like to make sure everything else checks out. Thanks again, Adam
  11. speedtool
    Joined: Oct 15, 2005
    Posts: 2,541


    Keep us informed...
  12. there is a Guy that makes a 6v + or - alternator add on e bay i had one worked grate

    the car can be wired aether way amp meter and coil have to be wired accordingly

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