Ign coil polarity

Anonymous-0 · Sep 27, 2009

I just helped a friend work on a Ford 9N that has been converted to 12V with negative ground (originally 6V w/positive ground). I remember there used to be concern with coil polarity. Does it make any difference?
The tractor is owned by a man who, in five months will be 100 years old, and he still mows with the tractor and still drives a car.

old · Sep 27, 2009

It does in fact effect spark a little bit but not enough to worry about. Plus on that type of coil there is no way to switch the way it hooks up so you either use it 12 volts - ground or go back to the 6 volt system so you can switch it back to + ground. Ya they make alternators that are + ground but they cost an arm and leg and most are a type that are a pain to keep working

Old Roy · Sep 27, 2009

God Bless the 100 year old. if a change over power should go to the + terminal.

John B. · Sep 27, 2009

Yes the polarity of the coil makes a big difference.

By changing the polarity of the coil you also change the current flow in the output side of the coil (spark plug wires) if spark doesn't jump the electrodes on the spark plug with the correct polarity it can cause problems such as premature failure. Coils are marked + & - for a reason.

Allan in NE · Sep 27, 2009

The electrical flow is reversed both at the points and the plug(s).

It will run, but not as efficient as it was designed to.

Allan

Bus Driver · Sep 27, 2009

For negative grounded systems, the coil negative terminal should be connected (by a wire in most cases) to the distributor (primary lead). For positive grounded systems, the coil positive terminal should be connected to the distributor. Those who disagree are completely free to use whatever system they choose.

Hobo,NC · Sep 27, 2009

convert it to a round can coil NAPA IC14SB and never look back,, the original 6V and the 12V square can coil are a P.O.S.,,, shed your self of the problem and have the best of the best,,, I guarantee anyone that has trashed the OEM coil and gone with a external round can coil will tell ya its the best thing they ever did to their N...

John T · Sep 27, 2009

Coils are indeed polarity sensitive.....Sure they will still fire at the wrong polarity but the system is more efficient if the polarity is correct........Also note its easier to emit electrons from a relatively hotter (electrode tip) surface to a relatively cooler (ground strap) similar to why theres a heater under the cathode in a vacuum tube.

For Pos ground the coils + goes to ground via the distributor and its points while the - wires to the ignition switch,........Opposite that for neg ground......

John T

old · Sep 27, 2009

But John on the front mount ford distributor the coil only has the one wire so you can not switch it around like the newer round can coil so you either have to stay with the 6 volt + ground or live with going to 12 volts and - ground

John T · Sep 28, 2009

Thats right Rich, unfortunately he just cant change polarity on that coil grrrrrrrrrrrrrr Better to stay at original ground maybe but if one insists on an alternator sounds like one of the expensive custom jobs.

Hope all is well down your way

John T

teddy52food · Sep 28, 2009

A magneto reverses the polarity every time it fires. Doesn't seem to make any difference.

old · Sep 28, 2009

As for the alternator he could always buy a brit Lucas one they are + ground but boy that in its self can open one big can of worms

Ign coil polarity

Anonymous-0

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old

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Old Roy

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John B.

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Allan in NE

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Bus Driver

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Hobo,NC

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John T

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old

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John T

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teddy52food

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old

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