POS or NEG ground

Jim Huseby said:
Again, I'm trying to make this simple, not difficult. Here's another answer to a couple posts on this thread. Swapping the coil leads can't change whether the spark jumps from the plug's center electrode to the ground electrode or vice-versa. If the battery is connected positive ground, the plug's ground electrode will be positive and the electrons will have to jump from the center electrode. If the battery is connected negative ground then the spark plug's ground electrode will be negative and the electrons will jump from the ground electrode to the center electrode . Swapping coil leads will determine whether the current going to ground through the points passes through the primary winding or secondary winding and therefor how high a voltage is induced to fire the plugs. THIS IS NOT ROCKET SCIENCE. The battery current must pass through the PRIMARY coil winding and through the points to ground, so that when the points open and the field created by the 6 or 12 volts passing through the PRIMARY winding collapses, a high voltage(what should it be, 20,000?) will be induced in the SECONDARY winding which will then discharge across the plug gap to ground. It is the ratio of coil primary windings to coil secondary windings that determines the voltage available at the plugs. If you vainly attempt to change coil polarity by swapping coil leads, you will lower the voltage to the plugs. And that,folks is why the windings are named PRIMARY and SECONDARY. About all coils today have their low tension terminals marked (+) or (-). That confuses most people and it shouldn't. Back when pos and neg ground cars were intermingling, you would find coils with their terminals marked "BATT" and "SW" (for points). Today, since most all cars are wired neg ground, the semi-literate manufacturers label the coil terminals "+" and "-"., and therefor the "+" means primary and the "-" means secondary whether it will be used in a positive ground or negative ground system. None of the components in a Model A ignition system are polarity sensitive.
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Well, kinda sorta. I understand you're trying to over simplify this. The condenser/capacitor is what really induces the secondary voltage and why the system won't work without it. But, I understand why you're saying it like you are. You're coming across as talking down to everyone, I don't think [hope] thats your intention.
 
Jim Huseby said:
is the condenser marked with a (+) terminal and a (-) terminal, and why?
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No because it will fit only one way, simple enough?

You don't like the answers so you ask again?

So let me answer again in terms even you can understand;

It's the plugs that care about polarity not the coil!
The condenser is not marked because it can go in only one way.
NEITHER side "stores" electrons more them the other.

If you have A POINT TO MAKE, MAKE IT!!!

You were given simple answers and not so simple answers but neither is making you happy, WHAT DO YOU WANT???????
 
I'm takeing it that way also.There is a correct way to connect the coil and its not any way that you choose. This will only be confuseing to people that don't know any better. This thread is silly and should be deleted.
 
I'm sorry, but I'm the one that's simple-minded and humble. I did not offer to explain this subject for any other reason than to explain a simple set of facts in a gentle way. My intent was certainly not to lure anyone into a position for them to get themselves publicly embarrassed. I did set out a set of simple questions that would help, if you calmly and intelligently thought them through, but some of you took it as some kind of personal attack instead of an interesting exchange. Now, I will be considering withdrawing facts in order to stay friends. I like having friends, especially ones who can toss ideas around, even if they disagree, until the light bulb comes on, or not. Still friends. But I won't change facts. As I said, I'm no guru of any kind and don't want to get involved in a test of intelligence, which I would certainly lose. The subject I originally started has no emotions and is not influenced by emotions.
 
"If the battery is connected negative ground then the spark plug's ground electrode will be negative and the electrons will jump from the ground electrode to the center electrode."

This is just flat wrong. Autos have had a negative ground systrem since the 50's and they fire through the center electrode, if wired correctly.
The coil does not care about positive or negative ground, only the direction of flow. Change the primary polarity connections and the secondary is also changed.

This can be tested easily. Take an analog voltage meter on highest setting, attach one lead to ground, the other to the plug wire, crank the engine and see which way the meter jumps. Reverse the coil connections, and the meter will jump the other way.
 
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GEEZ! "THEORIES" & CONFUSIONS abound!! It's a simple car, just hook it up for positive ground, hook up the coil properly, just like it left the factory & worry about something important, like changing the oil & greasing 91 fittings & oiling yo horn! Bill W.
 
BILL WILLIAMSON said:
GEEZ! "THEORIES" & CONFUSIONS abound!! It's a simple car, just hook it up for positive ground, hook up the coil properly, just like it left the factory & worry about something important, like changing the oil & greasing 91 fittings & oiling yo horn! Bill W.
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Very well stated!
 
Here's a nice wiring diagram that some good citizen posted years ago (sorry, I can't identify who deserves the credit.)




Here's a close up of the coil wiring.



The thinner wiring is the secondary winding. If the diagram were more accurate, there would be about 100 times as many turns of it as of the heavier primary wiring.

MOST IMPORTANT: Notice that one end of the secondary winding is connected to one end of the primary winding. This ultimately determines how the polarity at the coil connections determines which way the electrons will be going in the secondary (and in the spark plugs). Here's how--

The goal is to have electrons flow down the center secondary wire that goes to the plugs. BUT, the electron flow induced in the secondary windings will be of the OPPOSITE POLARITY (i.e., direction) as the current in the primary windings. Thus--if you focus on the junction point where the primary and secondary windings connect--in order to get electrons to flow FROM that point, thru the secondary windings, and then on to the plugs, the electron flow in the primary windings must to be TOWARD that point. And, it is that direction of electron flow in the primary windings that you determine when you connect the battery to the coil. The electrons will be going the right way if that primary/secondary junction point is connected to the positive battery terminal, and the other end of the primary to the negative battery terminal, from whence cometh the electrons.

Since that primary/secondary junction point is internal to the coil, you need some external marks to let you know what's what, hence the "+" and "-" notations commonly used. Of course, only one of these connections will be by an actual wire path that you can trace back to the battery; the other will go to the ignition points to ground and back to the battery thru the sheet metal, etc.

On a correctly wired, positive ground Model A, the "+" coil terminal must connect to the ground, or ignition points, side of the circuit. That is the red wire in the diagram. The "-" coil terminal must connect to the "hot" wire coming from the battery via the starter and the ammeter. That is the black wire in the diagram. On a negative ground car, the opposite connections would apply. If you have a coil whose terminals are marked something like "SW" (switch) and "CB" (contact breaker), rather than "+" and "-", you have to know whether that coil was for a negative or positive ground car.
I hope this helps.

Steve
 
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When I commented that the schematic should have the + and - on the battery identified, I was neither advocating or condemning positive or negative ground on a Model A. I was merely pointing out that the addition to the schematic (a very good one) might save some confusion down the way for a less experienced Model A owner/restorer trying to wire his car as it came from the factory.

I wish I had as much spare time on my hands as some of you folks do.
 
amodel25 said:
When I commented that the schematic should have the + and - on the battery identified, I was neither advocating or condemning positive or negative ground on a Model A. I was merely pointing out that the addition to the schematic (a very good one) might save some confusion down the way for a less experienced Model A owner/restorer trying to wire his car as it came from the factory.

I wish I had as much spare time on my hands as some of you folks do.
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I wonder where your comment is--I don't see it above.

Otherwise, retirement is a wonderful thing!

Steve
 
'Nice schematics, Tom and Steve. Especially of the coil. It looks like I stand corrected and publicly embarrassed myself. Nevertheless, thanks all for your frankness. I see that my mistakes were not looking at my own schematics and assuming that switching coil leads would force the primary and secondary windings to swap roles. Thanks for your clear explanation and for explaining that the high voltage discharge from the coil will be opposite the coil's low tension polarity. You can spank me, or use a ball bat.
 
No problems Jim,

The superb quality of the sheet metal work that you do, and the honesty by which you run your business speaks for itself and by far outweighs any annoyance over you being mistaken on a subject which is anway regarded as black magic by 50% of model A owners.



Jim Huseby said:
'Nice schematics, Tom and Steve. Especially of the coil. It looks like I stand corrected and publicly embarrassed myself. Nevertheless, thanks all for your frankness. I see that my mistakes were not looking at my own schematics and assuming that switching coil leads would force the primary and secondary windings to swap roles. Thanks for your clear explanation and for explaining that the high voltage discharge from the coil will be opposite the coil's low tension polarity. You can spank me, or use a ball bat.
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Admitting being mistaken is FAR less embarressing than sticking to your guns when you're wrong, just for the sake of it!

Well done!
 
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