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Technical 6v positive ground

Discussion in 'The Hokey Ass Message Board' started by AZguy, Apr 24, 2017.

  1. AZguy
    Joined: Jul 24, 2011
    Posts: 49

    AZguy
    Member
    from Tucson, AZ

    I just picked up a 50 lincoln that is 6v with positive ground. My 40 Plymouth was the same way so it wasn't anything new. It's been cranking insanely slow and is hard to start because of it so I looked and the last owner put a new 6v battery in but it's hooked up negative ground but since he used 2 red battery cables I never noticed.

    Could that explain my slow crank? Also before I noticed it was backwards I checked the voltage when it was running and was only getting like 6.5 volts at the battery, could that be related too?

    Can I just switch the battery back around or do I need to do something else too?
     
  2. tubman
    Joined: May 16, 2007
    Posts: 4,313

    tubman
    ALLIANCE MEMBER

    You really don't know what you have. I'd disconnect the battery and start looking for evidence of a polarity change. If you can't find any, I'd change it to positive ground and give it a try. There are a lot of ignorant folks out there that have no knowledge of these old systems and would do some stupid things. Is there anyone around that has some knowledge of this that you can get to help you? Step back and try to understand what you have.
     
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  3. cs39ford
    Joined: May 1, 2012
    Posts: 751

    cs39ford
    Member

    After you check out system. I would also make sure it's a heavy cable not one for a 12 volt system. That could make it crank slow also
     
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  4. tom in nh
    Joined: Oct 16, 2011
    Posts: 64

    tom in nh
    Member

    Clean yer grounds. Especially look for paint on your starter / engine block, etc. effectively becoming a barrier if it has been spiffed up (rebuilt, etc.). Should be bare like tits without a bra.
    Good luck.
    Tom
     
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  5. R Pope
    Joined: Jan 23, 2006
    Posts: 3,310

    R Pope
    Member

    Does the ammeter work right? If it says "charge" when you first turn on the key, you have the wrong polarity.
     
  6. AZguy
    Joined: Jul 24, 2011
    Posts: 49

    AZguy
    Member
    from Tucson, AZ

    There isn't really anyone that I could ask about this near me. It doesn't look like anything else has been messed with except for the battery cables and battery. What should I be looking for? The big thing he even said it was positive ground which I expected since I knew these cars were positive ground before I looked at it. He took it to a shop before we bought it to add an electric fuel pump and go through the carb and im not happy with the work they did, wouldn't surprise me if they just mixed it up and put it in backwards.

    Actually I didn't even think about that. They used those cheap pre connected battery cable sections for modern cars from auto zone or something, so I'm betting their rated for the 12v system. I think I have some welding cable I can use to replace those with.
     
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  7. AZguy
    Joined: Jul 24, 2011
    Posts: 49

    AZguy
    Member
    from Tucson, AZ

    There are some added wires, I had assumed he hadn't just replaced them because the wires were worn but maybe he converted it to negative ground then.

    IMG_4376.JPG IMG_4378.JPG IMG_4376.JPG
     
  8. Which side of the coil has the power wire to it? (Not the one that goes to the Distributor)?
     
  9. Truck64
    Joined: Oct 18, 2015
    Posts: 3,452

    Truck64
    Member
    from Ioway

    There's yer problem. Throw it all out, and replace with at least 1/0 AWG stranded cable w/ crimped heavy duty plated copper clamps. All of them, to block, solenoid, firewall, starter etc. Charge the battery back up with a charger.
     
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  10. Alaska Jim
    Joined: Dec 1, 2012
    Posts: 270

    Alaska Jim
    Member

    rev the eng. up to about 1500 rpm and check generator output at battery. should be charging approx. 7.5 volts. if not you can adjust the volt regulator . also make sure that the car is polarized correctly. ck battery voltage before and after starting. this will tell you if it is charging, but like I said previously , to be correct it should be about 7.5 volts
     
  11. AZguy
    Joined: Jul 24, 2011
    Posts: 49

    AZguy
    Member
    from Tucson, AZ

    Yea I'll do that, I didn't even think about that because the cables look normal since I'm more familiar with 12v systems.

    Yea I revved it up and checked yesterday and it was only reading about 6.5 volts at about 1500 rpm, so it was only charging about .3 volts that's when I realized something was going on. If the car isn't polarized correctly could that explain the generator not charging? How can I tell which way it's polarized?
     
  12. Time for a shop manual. Either Ford, or Motor.
     
  13. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,683

    Bruce Lancaster
    ALLIANCE MEMBER

    And on the polarity...Ford products (without radio, electronic stuff) do not care about polarity as long as charging system has been polarized to battery and coil is hooked up correctly. Generator is fine either way once polarized.
    I'd go back to stock polarity just to keep everything straight and clearly mark the bat terminals!

    Polarizing '39-64 Fords: Do NOT try other ways, because half the people out there will tell you GM system, which will fry contacts because they use a different ground path!

    A) Disconnect the wire at the regulator terminal marked FLD and use it to momentarily (no longer than 2 seconds) touch the wire to the BAT terminal. There may be a brief spark; this is normal

    B) Reconnect the wire to the field (FLD) terminal

    C) Start vehicle and check charging system for proper operation

    This sets gen and reg to work on whichever way battery is hooked at the time of polarizing, and is same for 6 or 12 V.
     
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  14. Truck64
    Joined: Oct 18, 2015
    Posts: 3,452

    Truck64
    Member
    from Ioway

    I don't know that it matters electrically but fwiw my Ford Shop manual sez disconnect both FLD and BAT terminals from the regulator, and momentarily touch them together. It would have the advantage of totally removing the regulator from the equation I guess. I always make it a point to tell people that the engine is not running in this procedure! Kids these days...
     
  15. AZguy
    Joined: Jul 24, 2011
    Posts: 49

    AZguy
    Member
    from Tucson, AZ

    I went to go replaces those battery cables and realized that the cables I got from Amazon are more like cables someone would use to hook up a car stereo amp or something. The strands are much thinner and more packed together and the insulation is a soft pvc type. Will these work or should I return them and get something else?
     
  16. AZguy
    Joined: Jul 24, 2011
    Posts: 49

    AZguy
    Member
    from Tucson, AZ

    Never mind I returned those cables, I don't feel comfortable with that "soft touch" insulation in the engine bay.
     
  17. d2_willys
    Joined: Sep 8, 2007
    Posts: 4,094

    d2_willys
    Member
    from Kansas

    Go to a Tractor Supply or some other farm equipment supply store and get the big battery cables there. I like to take the positive ground cable directly to the engine, so that there is less chance of voltage drop from bad connections. Then take ground braids from engine to chassis and body.
     
    54vicky likes this.
  18. 3banjos
    Joined: May 24, 2008
    Posts: 459

    3banjos
    Member
    from NZ

    I vaguely recall being told a simple shorting method to reverse polarity, if you want negative ground.
     

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