04-04-2017, 02:54 PM | #1 |
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Coil Polarity
I have seen many wiring diagrams of the Model A ignition system but when they show the coil they don't show what wires go to the + and what goes to the -. The black wire is coming from the ammeter and the red to the ignition switch. I currently have the black to the + on the coil and the red to the - on the coil. Is this correct for the proper polarity. I have tried the lead pencil trick but my eyes are not as good as they once were and I'm not sure if I am seeing the flair. Thanks for any help.
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04-04-2017, 03:18 PM | #2 |
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Re: Coil Polarity
I use one of these.
Documents Model A Polarity Tester Simply place this unit between the distributor cap and the coil wire, and it indicates if you have the wires on your coil properly as well as if you have spark or not. Comes with complete usage instructions, genuine Nu-Rex. U.S.A.
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04-04-2017, 03:31 PM | #3 |
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Re: Coil Polarity
If you have a stock positive ground system then the red goes to the +.
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04-04-2017, 03:31 PM | #4 |
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Re: Coil Polarity
The ignition switch heads straight to the points, then ground, so on a positive ground car, the red wire connects to the +.
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04-04-2017, 03:32 PM | #5 |
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Re: Coil Polarity
Yep... what Bob C said. 8^)
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04-04-2017, 05:52 PM | #6 |
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Re: Coil Polarity
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04-04-2017, 06:02 PM | #7 |
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Re: Coil Polarity
I have a 6volt coil for my run-in stand. It does not say + or - it has "bat" and "dist" written on it. I think I've got it hooked up right. . Jeff
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04-04-2017, 06:42 PM | #8 | |
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Re: Coil Polarity
Quote:
Best to just connect it and then check for spark polarity. If anyone doesn't know about checking for spark polarity, just do a Google search for "coil polarity" and read the one by chicagolandmgclub. |
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04-04-2017, 07:06 PM | #9 |
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Re: Coil Polarity
Your better off with a coil that is marked +. Or -- So you know exactly how to wire it.
As Tom said one marked dist / batt could be intended for a neg ground system. If thats the case then you would hook up the Batt to the dist and the dist to the Batt for a pos ground car. I also have the tool ZZ posted |
04-04-2017, 07:54 PM | #10 |
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Re: Coil Polarity
Coil polarity should match battery polarity.
Neg ground battery, neg coil to ground/points Pos ground battery, pos coil to ground/points |
04-04-2017, 10:13 PM | #11 |
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Re: Coil Polarity
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04-05-2017, 11:05 AM | #12 |
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Re: Coil Polarity
Thanks for the help. I have it hooked up right now and with the pencil I think I see the flair toward the plugs.
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04-05-2017, 11:30 AM | #13 |
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Re: Coil Polarity
and tell me wmws..... have you noticed any difference of the running of the engine with the polarity switched either way? I certainly haven't noticed any difference on my A with it either way... but if it revved to 4000 or more I guess that could be a different matter
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04-05-2017, 11:38 AM | #14 |
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Re: Coil Polarity
I drove my Model A for 2 years with the coil wired wrong, and it never made any difference. Only when you need max voltage to fire the plugs you might feel a misfire.
The coil output is the same either way, but when the hot center electrode is negative it fires easier. |
04-05-2017, 01:06 PM | #15 |
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Re: Coil Polarity
I have one Model A coil that doesn't have any markings on it.
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04-05-2017, 01:51 PM | #16 |
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Re: Coil Polarity
Yep. You only should notice any difference under extreme conditions. Wrong coil polarity can reduce output by 20-30%.
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04-05-2017, 02:31 PM | #17 |
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Re: Coil Polarity
No I don't notice any difference in performance but if it is that easy to have it the right way why not have it right.
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04-05-2017, 02:50 PM | #18 |
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Re: Coil Polarity
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04-05-2017, 03:32 PM | #19 |
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Re: Coil Polarity
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04-05-2017, 03:34 PM | #20 |
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Re: Coil Polarity
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