Ignition coil polarity

There has been some discussion about ignition coil polarity at the Ford area of these forums. I disagree with a few of the comments made.
Note - in my opinion, nobody yet has a full understanding of how electricity works. Electrical systems are based on several unproven theories and predicted behavior (based on past behavior).

When it comes to ignition polarity - it has been clearly demonstrated for over 100 years - that spark-plugs are somewhat polarity sensitive.
Subsequently, coil polarity has some importance.

Some of my older auto and tractor manuals claim a coil's max output at the spark-plug can be 30% less if the polarity is wrong with certain coils. I do NOT claim to have done much testing myself.

Superturbodiesel wrote . . .

?Ignition coils are not designed to work only for a specific type of grounding. They can be used on a positive or a negative grounded battery system, meaning that they will work with either type of grounded system.?

From what I have read - that is not universally true.

JMOR

?Almost any honest person will never know the difference whichever way the coil is connected. Their will always be somebody that swears that they reversed their coil and got better results......but can never prove it. ?

I suspect it is hard to prove unless in a "make or break" situation.

In a 4 cylinder magneto, 2 plugs fire positive & the other 2 fire negative.

so how did you come up with that statement as we would like to know

John good info, THANKS for that post, you're handy to have around. Your picture is something most engineers and electrical and automotive techs are familiar with, even if many non electrical trained gents may NOT be. Over the years I've seen several similar explanations to that you posted by different authors and vendors, but they all basically described the SAME concept. IE its best to operate a coil at the labeled polarity.

For any nay sayers who say it makes no difference, I would ask THEN WHY DO COIL MANUFACTURERS GO TO THE EXPENSE AND BOTHER TO LABEL COILS ?????? If it doesn't matter they wouldn't have to place + and - or BAT and DIST etc. on coils now would they ????

A few years back my late friend Duane Larson, a Nuclear Physicist, performed an experiment in his shop where he measured at what voltage a coil fired, and if the coil was at reverse polarity the voltage had to be a few thousand volts HIGHER !!!! In laymans terms at reverse polarity the coil had to "work harder" and run a tad hotter and it wasn't as efficient as if wired correct.

If anyone here is old enough to understand how vacuum tubes work, they know the reason why there's a heater under the Cathode, is because its easier to emit electrons off a relatively HOTTER (heated Cathode) to a relatively COOLER (Anode) surface, I believe that's referred to as thermionic emission. In an engine the plugs ground strap is much cooler then the tip sitting out there in the hotter combustion chamber.........

THAT BEING SAID HOWEVER as a past used tractor dealer and farmer and having seen and worked on literally hundreds of old truck n tractor coil ignitions (some wired right others not) they can still run at reverse coil polarity and to many non critical casual observers and users its NOT like the difference is night and day. Many might not ever know the difference LOL

Of course iffffffffffff ?? a magneto fires at each (BOTH North and South) rotor magnets passing, one spark is at one polarity and the other is reversed, but yet they still perform.

As an electrical engineer I must respectfully disagree with your opinion "nobody yet has a full understanding of how electricity works"

Hey we sent a man to the moon and are typing on our computers so even if you don't understand how electricity works, I disagree that "NOBODY" understands how it works lol. I will say that when I studied EE the absolute hardest subject I took was "SOLID STATE PHYSICS, ELECRTRONICS OF SOLIDS" That dealt with quantum mechanics and electron and particle theory and complex physics and so called electron and hole theory and even Maxwells Equations DEEP DEEP COMPLEX SUBJECT. BUTttttttt even if some students (MEEEEEE) didn't fully understand all that, OUR PROFESSOR SURE DID. Of course electron theory and solid state physics CAN NOTTTTTTTTTTT BE EXPLAINED HERE, it can take yearssssssssss to grasp such a deep subject so do not ask or even think I can explain it here lol.

You cant prove NOBODY understands how electricity works and I cant prove SOMEBODY understands, so we will just have to respectfully disagree and allow each other our own "opinions" NOT A PROBLEM FOR ME I'm NOT qualified to explain or prove it grrrrrrrrrrrrrr

Hope this helps gents understand why its best to operate an ignition coil at its labeled polarity even if it cant be explained here in a few sentences (but neither can brain surgery)

God Bless, Happy Easter

John T Toooooooooo long retired and rusty EE with "opinions" but don't ask me to prove or disprove them, I'm too darn old for that lol

Teddy, FWIW that's also my understanding. Ifffffffff ?? a mag uses BOTH the North and South magnets passing by the coil to induce voltage, then one will be at opposite polarity of the other. Of course they still work.

John T

I guess it depends on what make and model magneto. At one time, Dixie high-tension magnetos were known for their constant polarity. It was called the "Mason" constant polarity principal.

EXACTLY that's why I posted ifffffffffff and ?? lol Many of the Wico used BOTH the North and South rotor magnet to induce coil voltage but I suspect the more complex more expensive mags maybe some of the Fairbanks Morse or others did like you say. That's why one should NEVER SAY NEVER

Thanks for the information John

John T

Some info on the "Mason" constant-polarity principal.

Some of the older John Deere models D and GP used one version of the Dixie made Magneto or an Edison Splitdorf with that beautiful polished Brass outer case PRETTIEST MAGS EVER MADE, bUt I wasnt aware which makes or models fired at the same polarity WHICH IS A GOOD THING IN MY OPINION.....

John T

Well, that CERTAINLY explains "The Mason Principle" in great detail.

GOOGLE doesn't seem to know much about it either.

That is a neat test, thanks.

A few points to bring up for those that have trouble understanding the importance of polarity of the spark.

Much like electrolysis polarity determines which piece will be the sacrificial metal.

Spark plugs of years gone by were built with material that would rapidly show wear if the polarity was incorrect.
Yes initially the engine will run fine but the accelerated wear will lead to running not so fine much sooner than if properly wired.

Early into the introduction of waste spark systems that fired half the plugs with polarity reversed spark plug manufacturers had to develop Iridium/Platinum etc plugs as the old technology plugs would not hold up.

So looking at the big picture I can not imagine manufacturers spending millions of dollars to change there product if the issue of polarity at the plug made no difference.

Indeed, As I best recall the last time I bought plugs the counter man asked if I wanted PLATINUM ORRRRRRRRRR DOUBLE PLATINUM. Ignition and plugs alike have come a long way since tractors of the thirties..........

John T

John ....... here is an interesting link about your friend that you mentioned in your post. Interesting guy .....
Untitled URL Link

(quoted from post at 08:09:18 03/31/18) In a 4 cylinder magneto, 2 plugs fire positive & the other 2 fire negative.

Click to expand...

hat is correct for a magneto, since it alternates between the North and South poles of the magnet, but not for a battery ignition system.

If using the pencil system, make sure you have a good insulator over the pencil, because if there is a hairline crack in the wood, the graphite center will conduct spark voltage to it and that spark will think you are the spark plug. And do NOT try substituting a mechanical pencil. :lol:

All of the manuals I have seen have always said that whichever lead of the battery goes to ground should be matched by the coil. Since the points provide the ground for the coil , if it is a + ground battery (most 6 volt systems) the + terminal of coil should go to distributors, and if it is a - ground battery (most 12 volt systems) the minus side of the coil to the distributor. I stick with the manuals.

What the heck does Google know? It cannot even spell GOOGOL correctly. That was the intended name but it got spelled wrong and too late now to correct.

Yep he was one fine man and one brilliant physicist, we worked on a few antique electrical issues together. At a GOG we had supper with him and Nancy not too long before his passing. He left a legacy in his JD Two Cylinder CD publication.

John T

He must have been a wizard at figuring things out. I clicked on the home page and then found this explanation of the JD firing order which he wrote. Too complex for me ....... it really is a complex way of firing two cylinders (which you'd think would be a relatively simple thing). Here's the link for readers who want a challenge ......
Untitled URL Link

Yeppers, many don't realize the left fires then only 180 later the right fires, but then its a 540 coast cycle before one fires again. Others think the pop pop pop pop is the left then right firing, but the sound the human ear hears is the combination of the two PER DUANE LARSON AND MY OWN UNDERSTANDING

John T