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12-05-2017, 09:29 PM | #1 |
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Positive or Negative Ground-What Difference?
What happens that should, and what happens that should not, when a 6 volt
battery is installed, grounding the Positive terminal in a Negative ground system OR visa versa? (Pre1960s systems-6 volt, generator, voltage regulator, etc.) Also, correct grounding for: 1950 Mercury V8 1953 Ford V8 |
12-05-2017, 09:47 PM | #2 |
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Re: Positive or Negative Ground-What Difference?
Common knowledge just says reverse the wire through the ammeter loop on the dash. Seems too little to me. I have done just that on about 5 or 6 trucks and it was fine.
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Owner/Operator of 'Jailbar Ranch' on the side of Mt. Pickett. Current stable consists of 1946 1/2 ton pickup turned woodie wagon with FH V8, 1947 Tonner Pickup (red) mostly stock with exception of a cummins 6at turbo diesel, 1946 Tonner Pickup (green) with 226 cu in 6 cyl flathead, 1979 Toyota landcruiser wagon, completely encased in 1947 Ford Jailbar sheet metal. Ok, cornbinder rear fenders..... 'Rusty ol' floorboards, hot on their feet' (Alan Jackson) |
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12-05-2017, 09:57 PM | #3 |
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Re: Positive or Negative Ground-What Difference?
The effect of changing polarity depends on what is hooked into the electrical system. With old Fords, all of the instruments except the Ammeter operate on resistance elements that do not care which way the current is flowing.
No radio will work on reverse polarity from it's design. If you have galvanometer type meter movements that work off of magnetic fields from current flow, such as a voltmeter, they will work backwards and may burn out. The regulator also depends on correct polarity. Why do you ask? What are you trying to accomplish? |
12-05-2017, 09:59 PM | #4 |
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Re: Positive or Negative Ground-What Difference?
Problems are the generator (which just needs to be polarized to work) and the coil. Running a coil with the polarity reversed drops the output down, something like 20 to 30 % I believe. And the items drolston listed.
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12-05-2017, 10:06 PM | #5 |
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Re: Positive or Negative Ground-What Difference?
But does revering the coil wires alleviate this problem? I have always heard the pole chosen for ground goes to the distributor.
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Owner/Operator of 'Jailbar Ranch' on the side of Mt. Pickett. Current stable consists of 1946 1/2 ton pickup turned woodie wagon with FH V8, 1947 Tonner Pickup (red) mostly stock with exception of a cummins 6at turbo diesel, 1946 Tonner Pickup (green) with 226 cu in 6 cyl flathead, 1979 Toyota landcruiser wagon, completely encased in 1947 Ford Jailbar sheet metal. Ok, cornbinder rear fenders..... 'Rusty ol' floorboards, hot on their feet' (Alan Jackson) |
12-05-2017, 10:11 PM | #6 |
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Re: Positive or Negative Ground-What Difference?
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12-06-2017, 02:28 AM | #7 |
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Re: Positive or Negative Ground-What Difference?
the correct grounding for the vehicles you inquired about is positive ground.
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12-06-2017, 02:38 AM | #8 |
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Re: Positive or Negative Ground-What Difference?
Supposedly when a coil has run a long time and polarity is swapped the iron core is adversely affected, the coil will work but the spark output won't ever be quite what it should be. I think Jim Linder (Bubba's Ignition Service) mentioned this.
Here's a link that discusses this polarity thing (although having nothing to do with the vehicle polarity!) it was found that a better spark occurs when the plug electrode is positive, as electrons like to jump from hot to cold. A coil will work when connected "backwards" but it will work best when connected correctly. http://mgaguru.com/mgtech/ignition/ig104.htm Last edited by Crankster; 12-06-2017 at 02:48 AM. |
12-06-2017, 06:46 AM | #9 | |
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Re: Positive or Negative Ground-What Difference?
Quote:
If you connect battery backwards for a short time, no damage will occur to pre-'60 cars. Myths - iron core of coils can be adversely affected with polarity reversal - FALSE - transformer cores assume a tiny residual magnetism but doesn't affect coil performance and is quickly reversed with polarity. Most coils will produce spark either way but they are wired to produce a greater voltage only one polarity Radios will not work - FALSE most will not work, a few actually will. Vibrator radios will not be harmed with reversing polarity. Some replacement solid state vibrators will likely be damaged unless the fuse blows first. Generic voltmeters (d'Arsenval) can be burnt out. FALSE the needle will likely be bent but the coils will take the same voltage either way without damage. I have worked professionally in above fields and hate to see these myths perpetuated. |
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12-06-2017, 11:29 AM | #10 |
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Re: Positive or Negative Ground-What Difference?
Ford started with negative ground back in the Model T days but they changed. The basic reason was that it is an advantage to current flow. It makes a 6-volt system a bit more efficient. With that low a voltage, the system needs all the help it can get. With a 12-volt system, the extra efficiency it so miniscule that the electrical system wouldn't notice the difference.
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