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Technical Explain to me about Positive ground

Discussion in 'Traditional Hot Rods' started by blazedogs, Mar 3, 2020.

  1. blazedogs
    Joined: Sep 22, 2014
    Posts: 470


    Working on a old 60,s engine today . It calls for positive ground, in my case a British engine.. I have run into this in the past with other projects.The last one was a old farm tractor Mpls Moline . Have never known why this is. What makes it positive ground and for what reason ?? Gene
  2. Because electricity flows out of the negative post
    H380, Flathead Dave and LOU WELLS like this.
  3. Battery positive is connected to the frame and negative is through the wiring.

    same principle as negative ground.

    you can switch to negative ground easily if you want

    switch the battery around
    Coil wires swapped
    Distributor depending on hei, electronic or points need to be switched

    ammeter if your still running one.

    No big deal about positive earth, other then it being different then what we are all used to.

    I think it was done for radio or ignition interference back in the day or some malarkey like that.

  4. that’s highly disputed both ways, not saying your wrong, but I cant answer that 100% either way as fact.
    pitman and Elcohaulic like this.

  5. If you store a car and pull the positive cable off the battery it will discharge. If you pull the negative off you won’t have a parasitic drain on your battery
    alanp561 likes this.
  6. anthony myrick
    Joined: Sep 4, 2009
    Posts: 8,147

    anthony myrick

    It’s for cars with reverse cut gears.
    Everything runs backwards
  7. Someone needs to take basic electrical and then advanced electrical at dealership. I got mine at Ford schooling in Carrolton Texas.
    stillrunners likes this.
  8. jimmy six
    Joined: Mar 21, 2006
    Posts: 9,502

    jimmy six

    Because the Prince of Darkness...Mr. Lucas thought it was a good idea.:rolleyes:
    town sedan, mr57, pitman and 12 others like this.
  9. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 3,397

    from illinois

    I know that the way you reverse an? HO train is by reversing polarity , same with a fan motor and a golf cart , so how's that work with a DC starter motor ??
  10. That's what happens when you put the steering wheel on the right side.

    6inarow, pitman, Driver50x and 7 others like this.
  11. blazedogs
    Joined: Sep 22, 2014
    Posts: 470


    Yes, Jimmy 6 Right I,m impressed(Lucas)
  12. 500caddy
    Joined: Feb 8, 2019
    Posts: 92


    I have heard that with positive ground you won’t have corrosion on the battery posts

    Sent from my iPhone using The H.A.M.B. mobile app
  13. Blues4U
    Joined: Oct 1, 2015
    Posts: 5,701

    from So Cal

    Electron's flow from negative to positive, but the flow of electricity is actually opposite that. As the electron's flow along a conductor, jumping from atom to atom, they leave an opening behind them. This is the "Hole Theory", which is the dominant theory of electricity. Hole movement IS electricity. While some people like to claim one or the other is correct, as a technician you can consider it either way.
  14. Blues4U
    Joined: Oct 1, 2015
    Posts: 5,701

    from So Cal

  15. Blues4U
    Joined: Oct 1, 2015
    Posts: 5,701

    from So Cal

  16. seb fontana
    Joined: Sep 1, 2005
    Posts: 7,034

    seb fontana
    from ct

    It doesn't care about polarity..To make a starter motor rotate in reverse the brush plate must be rotated 90°.
    Truck64 likes this.

  17. well, someone put some facts together!!!
    Thank you for that.
    Blues4U and upspirate like this.
  18. funny I was going to ask this 1956 Dodge - positive ground....had a 1954 Dodge Little Ram put in it....has always seemed to run okay around the yard with a little missing....never have done anything to the motor exceprt a carb refresh over the years.........had it maybe 20 years or so........
  19. Mimilan
    Joined: Jun 13, 2019
    Posts: 896


    Lucas is also responsible for the first intermittent wipers, and the self-dimming headlamp.
  20. Hemi Joel
    Joined: May 4, 2007
    Posts: 1,030

    Hemi Joel
    from Minnesota

    Electricity flows in a loop, so everything electrical needs at least 2 paths for the electricity for flow thru it. One path from the power source to the component, and another path back to the power source. When they build a car, they save wire by not running 2 wires (a + and a -) to everything. They run a cable from the battery to the chassis (ground). One side of each electrical component is either internally or externally connected to the chassis. (ground) Then only one wire to complete the circuit from each component to the battery. Now the electrical loop goes from the battery, thru the needed cables, fuses, wires, and switches, to the component, to the chassis, to the ground cable, to the battery. The only difference between positive ground and negative ground is wich side of the battery is connected to ground, as well as any polarity sensitive components.

    THere is nothing wrong with positive ground. No reason in the world to change it if you are keeping the stock electrical system in place. Just make sure to hook up the battery the right way, observe polarity when charging or jumping. If you want to run a neg ground radio or something, just add a converter, or isolate the component from ground.

    If you are swapping in a an engine with 12V negative stuff, you might want to convert the car over. Bulbs, starters, relays, solenoids, cig lighters usually work either way. Generators, alternators, radios, electronic ignition or electronic anything are polarity sensitive and need to swapped if you change the system. Heater fans you need to test, it could go either way. Obviously mechanical gauges are unaffected, but electric gauges probably need to be swapped if they are internally grounded, or rewired if they are externally grounded. Points don't care, swap the coil wires. I hope this helps.
    Last edited: Mar 3, 2020
    pitman, alanp561, LOU WELLS and 2 others like this.
  21. lake_harley
    Joined: Jun 4, 2017
    Posts: 1,486


    Lucas light switches have 3 positions; Off, Dim, and Flicker.

  22. Diavolo
    Joined: Apr 1, 2009
    Posts: 815


    My understanding is that positive grounding increases galvanic response (rusting) of the body and cables where negative ground corrodes the terminals instead. Easier to fix.
  23. And warm beer.
  24. Beanscoot
    Joined: May 14, 2008
    Posts: 2,053


    I thought the advantage of negative ground was because spark plugs worked ever so slightly better when the 'lectric jumped from the center electrode to the outside, or vice versa.
  25. 41rodderz
    Joined: Sep 27, 2010
    Posts: 5,421

    from Oregon

    I thought it was a persons attitude:oops:
    Last edited: Mar 4, 2020
    LOU WELLS likes this.
  26. Mimilan
    Joined: Jun 13, 2019
    Posts: 896


    That was from their refrigeration dept!

    At least their vacuum cleaners didn't suck
  27. BJR
    Joined: Mar 11, 2005
    Posts: 6,998


    What color is the sky in your world? This is just wrong.
    Blue One, Driver50x, Blues4U and 2 others like this.
  28. Truck64
    Joined: Oct 18, 2015
    Posts: 4,765

    from Ioway

    As far as electrons go, a spark "likes" to jump from hot to cold, the center spark plug electrode is far hotter than the ground electrode so consequently it takes less ignition coil energy buildup to start the spark from there.

    An ignition coil (transformer) will work either way it is wired, but it takes something like 20 to 30 per cent less energy to initiate the spark when wired properly.

    Interestingly enough this has nothing to do with whether or not the car is positive or negative ground!

    Don't really understand it (I just work here) and make sure my ignition coils are wired correctly. It probably wouldn't show up at idle, though maybe on a long uphill pull or hard acceleration, something like that.
    town sedan likes this.
  29. Truck64
    Joined: Oct 18, 2015
    Posts: 4,765

    from Ioway

    I've learned not to discount crazy sounding shit. I haven't had any batteries discharge by being disconnected though.

    Carmakers (mostly) switched to 12 volt negative ground in 1956. Elvis was drafted not long after. So.
    town sedan and dudley32 like this.
  30. Boneyard51
    Joined: Dec 10, 2017
    Posts: 5,029


    Folks, when you disconnect either cable from your battery, it interrupts the circuit! Makes no difference which one you disconnect it will eliminate the parasitic draw! It makes no difference as to positive or negative ground as long as components are compatible! Some things are polarity sensitive, some are not. If you have a permanent magnet motor, simply reversing the cables will reverse direction. If you have wire wound field motor, you have to reverse the direction of the current in the fields to reverse the direction. That’s why some motors do and some do not! Simple!

    Last edited: Mar 3, 2020
    alanp561, j-jock, 2OLD2FAST and 2 others like this.

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