Change of spark plug polarity

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration
Model T Ford Forum: Forum 2010: Change of spark plug polarity
Top of pagePrevious messageNext messageBottom of page Link to this message  By Arnie Johansen on Wednesday, July 07, 2010 - 05:39 pm:

When operating in the battery mode of ignition is it possible to change the center spark plug electrode polarity by switching the two leads of the primary coil inside the wooden coil box. That is, take the primary coil lead that is connected to the bottom contact of the coil and replace it with the other primary lead and then take the lead that was originally connected to the bottom button of the coil and attached that lead to the capacitor/points. In other words switch the primary leads inside the coil box.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Wednesday, July 07, 2010 - 06:11 pm:

Arnie, what purpose do you have in this ??


Top of pagePrevious messageNext messageBottom of page Link to this message  By Arnie Johansen on Wednesday, July 07, 2010 - 09:33 pm:

The literature states that electrons flow more readily from a hot body to a cold. By making the electrons flow from the center electrode of the spark plug it is said to improve performance.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Wednesday, July 07, 2010 - 09:39 pm:

Arnie. that is what happens in a gasoline engine with spark plugs...... trying to re-engineer 100 yr. old technology ??


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Wednesday, July 07, 2010 - 09:59 pm:

Center electrode should be negative. Put a graphite pencil in line with the spark plug lead that is disconnected from the plug. If a flare occures towards the plug, the wiring is correct. If the flare occures towards the lead, the wiring is reversed. The reason is what Arnie stated and because of electode erosion concerns.

I have no experience with the T coils, my car has a distributor, but I understand that the mag can put out negative or positive depending on the location of the magnets and where the timing is set.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Wednesday, July 07, 2010 - 10:07 pm:

Arnie,

What is the source of this "literature"? The Society of Automotive Engineers? Or an unnnamed "expert"?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary H. White on Wednesday, July 07, 2010 - 10:11 pm:

Isn't the HV current from the T coils alternating? Or is it more properly pulsating DC?
In the more modern point, distributor, coil system the spark to the plug is created by one DC pulse from the points to the coil and therefore the high voltage spark is polarized. The T coil's function is to create a high voltage via generating an AC current, stepping it up and sending it to the plug. Being AC it isn't polarized. That's my thinking anyway.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Wednesday, July 07, 2010 - 10:17 pm:

The magneto low voltage current TO the coil is AC voltage. The high voltage output FROM the coil to the plugs is DC.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Wednesday, July 07, 2010 - 10:34 pm:

Arnie clearly stated in the first eight words of the first post to this thread, "When operating in the battery mode of ignition..."

Yes, the HV current from the T coils is AC because of ringing - the effect of the capacitor connected to the inductive primary of the coil.

The polarity of the first spark depends on the polarity of the AC wave from the magneto when the points break and obviously, this depends on the relationship between the timer and the flywheel.

The first arc (the most important one) is the most intense can be either positive or negative in polarity when operating on the AC output field coil.

Not so when operating on battery - the subject of Arnie's thread.

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman on Wednesday, July 07, 2010 - 10:39 pm:

Well heck! That's just what I was gonna' say Seth, but you beat me to it!


Top of pagePrevious messageNext messageBottom of page Link to this message  By GLEN CHAFFIN on Wednesday, July 07, 2010 - 11:18 pm:

The output of a coil is always alternating whether the input is alternating or direct current. The points make and break the input current which makes the output always alternating.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Wednesday, July 07, 2010 - 11:30 pm:

Seth you are extremely confused.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Wednesday, July 07, 2010 - 11:48 pm:

John Regan can decide that. He seems to be the final word around here on all things electrical.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kim on Wednesday, July 07, 2010 - 11:59 pm:

Radio valves, they had a heating element to make the electrons flow one way


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Thursday, July 08, 2010 - 02:26 am:

Royce asked:"Arnie,

What is the source of this "literature"? The Society of Automotive Engineers? Or an unnnamed "expert"?"

It is a well known effect called thermionic emission. Here is a link

http://en.wikipedia.org/wiki/Thermionic_emission

Here is a link to an IHC manual which talks about the situation.

http://www.tpub.com/content/firetrucksandequipment/TM-5-4210-230-14P-1/css/TM-5- 4210-230-14P-1_545.htm

I agree with Seth's post explaining the nature of the coil discharge. He doesn't seem confused to me.

Glen, I don't understand what you are saying.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Noel Keefer on Thursday, July 08, 2010 - 02:39 am:

Seems everyone has had a say on this post.

Now for the basics of the truth!!

Seth has presented the truth, dead on the head.
With one exception.(:-(

Seth, on a distributor ignition car the polarity of the HV can be random.
Explanation, a poorly kept car with poor plugs can miss the first high energy alternation and for some inexpliczable reason, may fire on the opposite polarity of the next (opposite polarity (and decaying)) alternation of the HV. This could be witnessed while watching the old ignition analyzers on the "O" scope.

I'm sorry to say this Royce. But it is you who is confused. Keep reading

Glenn, Your explanation is arguable or needs completion/clarification. I easily and readily assume the later.

Gary,
The HV output is alternating, ie: swings + & - With respect to, not ground, but to the 12 volt terminal. It is series tuned by the capacitor. It isn't pulsating which means the polarity is unidirectional fixed to its reference.
A +12 volts is tied to one terminal of the coil, ya know, the one with the + sign. The points are tied to the - terminal. The Primary first goes to ground as the points close and then shoots up positively to a shocking high voltage, (200-400 volts) if connected properly. The primary voltage ďringsĒ and is AC. The HV is the same phase and, of course, the same frequency, as the primary. The HV winding has many more turns than the primary and is connected in such a manner, if connected properly, that this ringing primary AC adds to the HV produced by the secondary.

You all do have the + and Ė signs on the coil connected properly, donít you?

The primary voltage has decreased over the years as the new solid state electronics have taken over coupled with new coil design. In fact I think the second alternation, as explained above, is severely decreased by a zener to protect the solid state switch that grounds the coil.

Neil,
The graphite pencil method of checking the plasma arc (spark) is an old technique that most have forgotten. Glad you remembered. Just be reminded the eraser end can bite you!

Kim, old timer,
The heated filament was usually encased in "Thoriated Tungsten" that freely emitted electrons and made an electron cloud around the hot cathode. It was the presence of the positive plate voltage that made the Radio Valve conduct negatively charged electrons from the cathode to the positively charged plate, (and current from the plate to the cathode! Let's not tackle this on this thread)


As Seth Sez, John Regan, now's your chance.

Respectfully to all,
The defender of the truth,


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Thursday, July 08, 2010 - 02:41 am:

Thanks, Arnie. With all my years working with vacuum tubes and point-contact ignition, I never made the connection.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Thursday, July 08, 2010 - 08:29 am:

Here is a typical picture of the situation Seth was describing.

trace

This is not a T coil, but rather something I found on the interweb. A T coil trace looks much like this, regardless of whether it is running on magneto or battery.

Noel, I have never seen any randomness of polarity on a coil and point distibutor system - frankly I have a hard time believing it, in fact I would have to see it to believe it.

As far as involving John Regan, he's a smart guy for sure, but there is plenty of knowledge out there - we should be able to figure this thing out without bothering him. I don't presume to speak for John, but he has told me that he doesn't like to get involved in some of these threads for various reasons.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Thursday, July 08, 2010 - 08:44 am:

Thanks Tom and Noel for your posts. I understand why John would not want to get involved and I apologize for bringing him into this.

Have a great day.

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Thursday, July 08, 2010 - 09:21 am:

Tom, your graph is showing the spark discharge event("Spark Burn Time Period") to be DC.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson on Thursday, July 08, 2010 - 09:37 am:

A Model T operating on the battery will have only one polarity to the plugs depending upon which side of the battery is grounded and, as Tom pointed out, how the secondary winding was installed.
When operating on the magneto the polarity to a plug will vary depending upon which side of the AC current pulse the coil is firing and how the secondary winding was installed.
If you would like to prove this to yourself place a neon tube on the spark plug of a running engine and take a look.
As for which way is better, that could only be proven with some very sophisticated instrumentation on an engine dyno. In a high performance engine it may matter, but I doubt it makes a material difference on a Model T.
One final point. The Model T and single point distributor systems are fundamentally the same, but the parts are organized differently. They operate very different when the ac magneto is added and the position of the points is changed.
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Thursday, July 08, 2010 - 09:40 am:

Royce, you're right. The spark discharge seems to me to be strictly DC. That is why I have a hard time buying Noel's random theory. Only the decay (ringing) is AC, but that is exactly what Seth said above.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Thursday, July 08, 2010 - 09:54 am:

The decay shown on the O-scope simulation does not represent the discharge at the plug. It is a measurable but insignificant residual voltage.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Thursday, July 08, 2010 - 10:04 am:

From what I've read here, some or most modern coil packs fire two plugs at once by tying one end of the secondary to each. One plug is fired at normal point in compression stroke, and the other plug is fired at same point in exhaust stroke. The next firing is the opposite condition. This largely eliminates erosion by alternating the DC electron flow across the gap.

That's how you get a zillion miles on plugs in new cars, even with their much hotter sparks.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Thursday, July 08, 2010 - 10:07 am:

I should mention again, Noel and Seth are still mistaken in their beliefs.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary H. White on Thursday, July 08, 2010 - 11:18 am:

A T coil is a electro-mechanical device designed
to:

1. Make a pulsating current from a direct current, low voltage source.

2. Step up the voltage via transformer action to generate a high voltage for the spark plug.

Output from a transformer is AC unless it is rectified and filtered to produce a DC current. There is no rectifier circuit in a T coil.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Miller on Thursday, July 08, 2010 - 11:31 am:

My two cents

1) A transformer or coil needs a collapsing magnetic field to transfer energy to the secondary winding. The input voltage can be AC or pulsating direct current. If pulsating DC is used, then the output of the coil will be pulsating DC and will be of a single polarity.

2) Most auto engines today use coil on plug ignition systems with a dedicated coil on each cylinder. Earlier systems in the ninties commonly used a coil with a floating secondary which used a "waste spark" principle where two plugs 360 degrees apart on the firing order fired simultaneously.

Modern plugs are more durable because of the platinum on their positive electrode. If you ever encounter an engine that has never had a tune-up that uses waste spark, you may notice the plug terminals are color coded bank to bank because they have platinum on only one electrode. Aftermarket plugs from the same suppliers will have platinum facings on both electrodes since the person doing the tune-up is usually unaware of this polarity.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Thursday, July 08, 2010 - 11:45 am:

Looking at the spark "en camera" in chamber, the voltage from the coil builds up until there is enough to jump the gap. Once the spark starts, the air in the gap is ionized, and the high resistance of the gap is lowered - a lot. I suppose ringing could jump the ionized gap, but don't know, and doubt if it has enough energy to matter.

Remember the high voltage Jacob's Ladder demonstration? A pair of wires are placed in a very narrow V, open at the bottom, and fed with a high voltage. Once the spark bridges the gap at the bottom, it climbs the V, following the heated, ionized air.

rdr
Victorville


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Thursday, July 08, 2010 - 11:51 am:

Thanks for the clarification on modern ignition, Tom. Dunno about today, but a dozen or more years ago people found you needed a smaller gap with platinum plugs for them to work reliably, yet the gaps are about .050" on modern ignitions. Still confused on that, I guess.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Thursday, July 08, 2010 - 01:07 pm:

Royce said:"The decay shown on the O-scope simulation does not represent the discharge at the plug. It is a measurable but insignificant residual voltage."

I agree.

Gary said:"1. Make a pulsating current from a direct current, low voltage source. "

That may happen, but it isn't needed.

then:"2. Step up the voltage via transformer action to generate a high voltage for the spark plug. "

True.

then:"Output from a transformer is AC unless it is rectified and filtered to produce a DC current."

Not true. The field only has to be changing for mutual inductance to occur. This can (and does) happen on a collapsing DC current.

I see that I just re-said what Tom said - oh well it's typed, so I will post it.

Ralph may be right about the ionization, but I agree, it don't matter. The important voltage is the first one to jump the gap.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Thursday, July 08, 2010 - 03:17 pm:

A fun read guys. Just wanted to clarify one point. The statement that high voltage is produced in the T coil via transformer action to generate the spark at the plug is not true strictly speaking. The turns ratio of the T coil is about 80 to 1 and typical step up via transformer action would produce only about 80 times the primary voltage which would be way short of the amount of HV that can jump a 1/4" gap. HV to jump a gap in free air at 1 atmosphere of pressure is generally taken as 75,000V per inch. The T coil is in fact wired like a typical transformer with a totally separate primary and secondary but in practice is works more like a typical "flyback" transformer in an older TV set. The output of the coil is determined by the step up ratio yes but also multiplied by the "Q" of the coil. Q or quality factor of the coil is defined by The the AC reactance of the coil divided by its resistance. That is were the extra voltage comes from.

Glad you let me sit this one out. I have a lot going on right now with the MTFCI tour coming up next week. I am chairperson for the youth auction and my wife is chairperson for the fashion show and I have several orders to deliver and I have 6 cases of cookies to pick up and I have a rear wheel on my T clicking and I have .........

Please bring things to the auction at the MTFCI tour in SD in a couple weeks - otherwise I look bad and Stan Howe (my auctioneer) will also look bad and may need to raise prices on rebuilt rearends to cover his losses. Just kidding.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson on Thursday, July 08, 2010 - 05:28 pm:

Tom
To add to my point above.
The diagrammed trace you posted above depicts what happens on a single point distributor system when running on DC.
If you look at an operating Model T coil running on the magneto with an oscilloscope it will show a similar trace when the magneto current pulse is one polarity and when the next current pulse arrives of the opposite polarity and the coil fires again it will show trace with opposite spark plug polarity.
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary H. White on Thursday, July 08, 2010 - 05:57 pm:

OK. My description of the workings of a coil was a bit simplistic and based on it working from a battery. Everyone seems to have their own idea of what AC and DC is. To me DC (direct current)is a consistant, unvarying current flow and is totally useless to a transformer. That's why it has to be chopped up into bits (the buzzing you hear) so the coils windings will see it as an alternating current and perform accordingly. In the modern spark system the coil gets one change of current provided by the points or sensor for each time the plug is fired. In the T's system the coil is turned on by the timer and will continue to provide a spark until turned off by the timer. If you could slow down the buzz rate of the coil you could see the plug repeatedly firing. Hence AC. That's it for me.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Thursday, July 08, 2010 - 06:23 pm:

That is just not how the coil works Gary but if that works for you I have no problem with that.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Thursday, July 08, 2010 - 06:26 pm:

Direct current has only one polarity.

Direct current chopped up into bits is still direct current.

Alternating current has both polarities - greater than the reference point of zero and also less than the reference point of zero.

Voltage varying on one side of the zero voltage reference is still DC.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Thursday, July 08, 2010 - 06:40 pm:

Gary,

You have a fundamental misunderstanding of how a Model T ignition system works. You ought to read the wonderful articles written by Steve Conniff and Ron Patterson on this subject. They can be found at http://www.funprojects.com


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Thursday, July 08, 2010 - 07:13 pm:

Regarding plug erosion, magneto AC power should result in far less erosion than DC. Has anyone found that to be significant?

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson on Thursday, July 08, 2010 - 09:33 pm:

Gary
Here are two articles we prepared a few years ago that are intended to provide a simple explanation of how the original Model T ignition system works and explain other quirks of the design.
I hope they will help you better understand how the Model T ignition system provides spark on the DC battery versus the internal AC magneto.
Model T Ignition System and Spark Timing
More on Model T Spark Timing
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson on Thursday, July 08, 2010 - 09:39 pm:

Ralph
I never paid much attention to spark plug erosion, but I certainly can attest to different Model T coil point contact point wear between operation only on battery and operation only on magneto. Obviously the difference is the magneto produces AC and the battery is DC.
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Thursday, July 08, 2010 - 09:47 pm:

Gary, now that I understand your terminology, what you are saying is essentially correct. I would have phrased it differently, but I get what you are saying


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Thursday, July 08, 2010 - 09:52 pm:

DC notching occurs when incandescent lamps are run at their rated voltage or above. The filament material (tungsten) migrates away from the negative end until it fractures. Vibration or shock hastens the failure. DC notching doesn't happen with AC voltage applied, of course, so lamps last up to five times longer on AC than on DC.

rdr
home


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Friday, July 09, 2010 - 05:47 am:

George Westinghouse might have given Thomas Edison a hard time about that, had he known. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money on Friday, July 09, 2010 - 09:21 am:

Seth, I underdatnd that the feud between Tesla and Edison continued during the 1893 Expo in Chicago. Edison got the contract to wire the Expo (some say underhandedly) and Tesla then claimed that since he had the patent on the AC bulbs he wasn't going to allow the AC bulbs to be used in the Expo. Maybe just folk lore but that is what I heard.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Friday, July 09, 2010 - 10:51 am:

Interesting Doug. It sounds plausible.

If folklore, some "mythbusters" here will likely chime in real soon. LOL!

Have a great weekend!

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Arnie Johansen on Friday, July 09, 2010 - 04:17 pm:

OK guys, my original question remains. Can one rewire the inside of an ignition coil as indicated in the first message of this thread?

The goal here is to make sure the pencil arc is as Neil stated in his message when operating in the battery only mode.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Friday, July 09, 2010 - 04:34 pm:

A Model T runs poorly on battery due to low voltage which affects coil ramp up which affects the amount of timing advance available.
You can swap leads at the battery a lot quicker than rewiring all the coils for the same result, which will be a Model T that runs better on MAG.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kim on Friday, July 09, 2010 - 04:39 pm:

i had a really bad idea that i did not think out at all.
Use a seperate mercury-arc rectifier for each spark-plug so you can be sure each one gets the polarity of spark you want


Top of pagePrevious messageNext messageBottom of page Link to this message  By Noel Keefer on Friday, July 09, 2010 - 04:51 pm:

TOM,
Now, as I have witnessed on my 69 Pontiac, if the plug doesn't fire on the first "ring" then the secondary swings negative and then the plug has another chance to fire. This time it will be of the waveform opposite in polarity.
In your diagram, which is a standard accurate diagram of the primary, if you removed the spark plug you would see a continuous oscillating decay of the voltage. Through mutual inductance coupling the secondary will be following the primary. So it will also be AC.

This is just an insignificant "what if" and is unworthy of a disagreement. ;-)

RICK:
As a magneto rotates and the N & S poles generate the voltage alternately, hence the plugs fire each way which extends the plug life. Single cylinders sure do. Good observation.
I've not given any thought whether a 4 or 6 cylinder follow this rule differently. Youíre an aviation guy, (as I am), maybe you can take the time to figure that out and tell us!


HAY, Thread followers, have we missed an important point regarding coils here? Letís review inductance a little.

With a constant AC input an 80:1 coil would boost the input voltage by 80 times, ie: 10 VAC input gives us 800 VAC output. This is a standard transformer function. We know we canít fire a plug with this!
Now the fun begins. Using 12 VDC as an example, when we close the points we generate an invisible energetic magnetic field around the primary by the current flowing through the primary. When the points open, this field of energy stored in the primary has no place to initially go, and it MUST go somewhere. So it collapses VERY rapidly and oscillates at a frequency determined by the coil and that important CAPACITOR. The rate of decay is a function of the quality of these oscillator components. This is called Q as Regan has explained. This causes the PRIMARY voltage to spike rapidly to 200-400 volts, (Ringing?). This, when multiplied by the 80:1 ratio, generates a theoretical --> "400 volts X 80 = 32,000 volts". (while I was setting up my coils I have obtained sustained arcs of over one inch!)( per Johnís rule, thatís over 75,000 volts!) ( DON"T do this on one of your good coils. It may breakdown and be one of your shot coils!!)

The plug doesn't need all of this voltage to spark and sparks at a lower voltage creating a lower resistance path for discharge. The magnetic field now "dumps" its energy into the load. The load, simply stated, is the secondary resistance of the coil (Around 4000 ohms?) and the spark resistance which is VERY low, (less than 50 ohms). This means that a spark is not an instantaneous arc but an arc with some duration. Instantaneous arcs don't ignite fuel as well as sparks with some duration. So all works well.

Modern cars use resistance wire and plugs. This causes an extension of this duration.

And, Dear Royce will get it someday. Keep reading and understand what you read, Royce.

Some of the above explanations contain some simplifications. This was to avoid any high falutiní math and theories.

Regards to all,

Noel, Defender of electrical truth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Noel Keefer on Friday, July 09, 2010 - 05:00 pm:

Royce,
I believe you understand the T with a mag per those two articles you refered to. Both of them are great sources of info. But when we talk batteries w seem to loose you. I hope the last coil review made sense to you.

Respectfully,

Noel, Defender of electrical truth

Please feel free to contact me off line and we can chat further.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kim on Friday, July 09, 2010 - 05:08 pm:

i had a better idea, four merucury tilt switches (one for each spark) with the contacts close together & plugset up so that one end was in the mercury all the time & the other end just above the mercury (but driving on hills the mercury would move & the current would flow any way it liked)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Friday, July 09, 2010 - 05:25 pm:

Noel,

The alternating input voltage does not affect coil output polarity.A Model T magneto is actually an AC Generator, not a high tension magneto like th Slick or Bendix units found in puddle jumper aircraft types.So the polarity at the plugs does not change whether a Model T is operating on BAT or Mag.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Noel Keefer on Friday, July 09, 2010 - 05:25 pm:

Royce,
I believe you understand the T with a mag per those two articles you refered to. Both of them are great sources of info. But when we talk batteries w seem to loose you. I hope the last coil review made sense to you.

Respectfully,

Noel, Defender of electrical truth

Please feel free to contact me off line and we can chat further.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary H. White on Friday, July 09, 2010 - 05:44 pm:

A well stired pot makes a fine stew. Ain't gonna beat this horse no more.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Arnie Johansen on Friday, July 09, 2010 - 06:20 pm:

Can someone answer the question in the first post? I understand that the system works better using the magneto, but my question is when the vehicle is operating under battery. It has been stated before that some plugs may have a different polarliy since each cylinder has its own ignition coil to operate from. For instance, if one takes a pencil and finds that the arc is to the plug on three cylinders and that the arc is going in the other direction on the fourth, my question is can I interally change the wire in the ignition coil of the fourth one, such that all four cylinders will have the "arc from the pencil" going towards the plug in the battery mode of operation? If that can be done, will my method of changing the wires inside the ignition coil result in change direction of the "arc from the pencil"??????


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Friday, July 09, 2010 - 06:33 pm:

Arnie:

YES you can reverse either the primary or Secondary windings end for end but NOT both. I would recommend that you mess only with the primary but you cannot simply exchange the top side terminal on the coil with the bottom terminal since you will be reversing the secondary too and may end up with the same polarity before you reversed it. If you want to try it - I would suggest you dig the tar out at the very base of the coil inside the coils box. One of those primary wires is very short and goes directly to the bottom connection while the other one goes up to one of the 4 bolts on the coil points. You will need to cut them both and switch them. That will switch ONLY the primary and thus you should then get opposite polarity from whatever you had. As others have stated, the polarity can thus only be one way when using battery for ignition since the magneto will alternate polarities between each spark pulse. I think that answers your question. You might find it easier to simply look for 4 coils that are alike in polarity and then rebuild those because it is a lot of work to dig out that tar and there is a very good chance of damaging the HV winding which is right next to the break out of the primary at the bottom of the coil winding. The end of the primary and thus the end of the core is sometimes only sticking out 1/4" or less below the bottom of the bottom HV "donut" winding. Be very careful or you will damage the HV winding.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Arnie Johansen on Friday, July 09, 2010 - 06:40 pm:

John:

Thanks for your reply to my initial question, especially when you are getting ready for the big event of the year. I hope you have enough soup cans and that the youth auction is a success!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson on Friday, July 09, 2010 - 07:41 pm:

Royce
I have to disagree with you that when a Model T is running on the magneto the polarity of the spark to the plug alternates.
If anyone out there does not believe this, come to my shop and in less than one minute I can conduct a simple demonstration on a running Model T that will prove it to you beyond any doubt.
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Friday, July 09, 2010 - 08:33 pm:

Now I'm REAL CONFUSED. So Royce MAY BE RIGHT!

Royce states above, "The alternating input voltage does not affect coil output polarity".

Ron states, "I have to disagree with you that when a Model T is running on a magneto the polarity of the spark to the plug alternates."

In my feeble-assed confused mind, this doesn't make sense.

PLEASE CLARIFY!

Seth, the dumbass mechanical engineer


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Friday, July 09, 2010 - 08:53 pm:

Ron is right. Depending on which node the coil fires, the spark could be positive or negative.

I will post a picture in my next post.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Friday, July 09, 2010 - 08:54 pm:

I suggest that anyone seriously interested in this issue drive his car to its maximum performance limit with a negative ground on the battery. Then he should reverse the polarity to positive ground, re-polarize the generator if one is on board and again drive his Model T to its maximum performance. If there is a discernable difference, he could then make the correct choice.

Do you think Ford recognized the error of his ways and reversed the polarity with the 1928 Model A using a positive ground? I think the choice of ground polarity is arbitrary, but could there be some logic to it?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson on Friday, July 09, 2010 - 09:01 pm:

Seth
My ineptly worded response!
When operating on battery the polarity of the spark to the plug does NOT alternate.
When the coils are operating on the AC input from the magneto the polarity of the output to the plug DOES alternate.
Ron the Coilmoron


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Friday, July 09, 2010 - 09:06 pm:

Well Tom, he isn't right if you reread his post. I agree with the fact that the polarity does indeed reverse, but reread Ron's first sentence - he is agreeing with Royce that the polarity can't change.

Ted,

I agree that is probably doesn't mean a damned thing. The engine is a neanderthal pig and I rather doubt it matters one way or the other, even with a Z head.

So, to answer Arnie's original question:

"You can't make a silk purse out of a sow's ear."

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Friday, July 09, 2010 - 09:12 pm:

No Ron, not inept at all, just un-proofread and I type too slowly. :-(

I agree with you 100%. Royce is the one that is "extremely confused" and "mistaken in his beliefs" and he needs to apologize for telling us that we are (Noel Keefer included). :-)

Have a great weekend.

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Friday, July 09, 2010 - 09:25 pm:

Early hit and miss engines had points inside the combustion chamber. A shaft penetrating the combustion chamber was turned due to cam action which in turn separated the points when ignition was supposed to occur. You just hooked up a battery to the points and away you went, almost. An important component was a wire wound multiple times around a large steel nail or steel bolt. The wire and bolt formed an inductor. The energy from the current flowing while the points were closed was stored in the inductor's magnetic field. When the points opened, the energy stored in the inductor "tried" to keep the current flowing, causing a hot spark.

As most of you know, this is basically the same as any spark plug coil, including a Model T coil, except that a secondary winding is added to build up the voltage even more. The rapidly collapsing magnetic field causes the high voltage, high energy spark. The T coil just does this multiple times instead of once as a distributor. From what Ron is showing, the polarity of the plug under mag could be plus or minus depending on the position of the advance lever.

I suppose one could add a bridge rectifer on the output of the mag to have a pulsating DC voltage and a constant polarity at the plug. Add a large capacitor and the timing could be continuous instead of depending on the position of the magnets. Has anyone done this?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Friday, July 09, 2010 - 09:34 pm:

You can't add a bridge rectifier to the output of the model T's mag because there isn't but one wire. The field coil is grounded, same as the spark plugs are.

If you added one diode, you'd get mono-polarity, but you'd only get every other spark when the timer grounded the coil.

Then you'd have 45 degree silly-assed timing steps when operating on magneto instead of only 22.5 degree silly-assed steps.

Seth (the "extremely confused" mechanical engineer)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Friday, July 09, 2010 - 09:40 pm:

All this stuff is rather trival and probably of no importance to the average T guy, but I find it interesting and like to talk to people who are also interested about it. Some folks get bored with these threads. Some folks get mad at these threads, but dad-gummit this is a discussion forum, we should be able to discuss if we want. I've been criticized for being too technical and for being not technical enough. Someone even sent me a private message saying that my posts disgusted them. I've decided that I don't care what other folks think, I'm not hurting anyone and will continue to post as I see fit.

Now that my rant is over, here are the graphs I promised.

1

This is a trace of the low tension side taken whilst driving at 46 MPH. You'll notice a couple of things:

All of the coil firings are on positive waves. The timer closes at approx. 125.5 ms and there is enough dwell for three firings. After the first firing (just before 127) the coil is operating as if on a hand-cranked coil tester. The reason the coil doesn't immediately fire on the next negative wave is that at 46 mph it just flat can't physically reset fast enough.

2

One this series it didn't reset fast enough to pick up the second positive peak, but rather went with the next negative one.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Friday, July 09, 2010 - 09:47 pm:

Neil asked:"I suppose one could add a bridge rectifer on the output of the mag to have a pulsating DC voltage and a constant polarity at the plug. Add a large capacitor and the timing could be continuous instead of depending on the position of the magnets. Has anyone done this?"

You can do it. You have to remove the ground from the field coil. Yes, I've tried hooking up a rectifier and a large electrolytic condenser, but it doesn't make the timing continuously variable, it is still "notchy", presumably because my condenser wasn't big enough.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Friday, July 09, 2010 - 09:48 pm:

A negative one? Royce said there can't be one of opposite polarity.

You MUST be mistaken, Tom. Your oscilloscope must be lying to you.

Seth :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Friday, July 09, 2010 - 09:50 pm:

Seth said:"Well Tom, he isn't right if you reread his post."

Wow, you're right. I read what he meant to say, not what he said.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Friday, July 09, 2010 - 10:13 pm:

BTW, Tom,

20,000 microfarads of capacitance is plenty to get excellent 12 volt DC (no silly-assed timing steps) ignition performance from Ron Patterson's coils without the need of a bridge rectifier and disconnection of the field coil's ground.

Seat of pants, of course, but WAY better than the horrible steps in ignition timing (the Ford way) when operating at lower engine speeds.

Been there. Done that. Would do it again if I ever buy another T.

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson on Friday, July 09, 2010 - 10:31 pm:

Tom
I explained that Thursday, July 08, 2010 at 09:37 am:
A Model T operating on the battery will have only one polarity to the plugs depending upon which side of the battery is grounded....
When operating on the magneto the polarity to a plug will vary depending upon which side of the AC current pulse the coil is firing....
If you would like to prove this to yourself place a neon tube on the spark plug of a running engine and take a look.
And again Thursday, July 08, 2010 - 05:28 pm:
The diagrammed trace you posted above depicts what happens on a single point distributor system when running on DC.
If you look at an operating Model T coil running on the magneto with an oscilloscope it will show a similar trace when the magneto current pulse is one polarity and when the next current pulse arrives of the opposite polarity and the coil fires again it will show trace with opposite spark plug polarity.
This thread reminds me of a quote by Sherif Ali in one of my favorite movies Lawrence of Arabia: "Truly, for some men nothing is written unless THEY write it"
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By Arnie Johansen on Friday, July 09, 2010 - 10:59 pm:

Tom:

What would the trace look like if one was driving at 25 mph rather than a fast guy like you going 46 mph?

Arnie

P.S. Perhaps none of this makes sense from a practical point of view, but it helps us understand the operation of the Model T ignition system!
Tom, I with you with regards to your "rant", if people do not like this discussion they do not need to read it!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Friday, July 09, 2010 - 11:00 pm:

Ron said:"I explained that Thursday, July 08, 2010 at 09:37 am:
A Model T operating on the battery will have only one polarity to the plugs depending upon which side of the battery is grounded.... "

of course

then he said:"When operating on the magneto the polarity to a plug will vary depending upon which side of the AC current pulse the coil is firing.... "

of course

then he said:"If you would like to prove this to yourself place a neon tube on the spark plug of a running engine and take a look. "

been there - done that.

then he said:"And again Thursday, July 08, 2010 - 05:28 pm:
The diagrammed trace you posted above depicts what happens on a single point distributor system when running on DC. "

true

then he said:"If you look at an operating Model T coil running on the magneto with an oscilloscope it will show a similar trace when the magneto current pulse is one polarity and when the next current pulse arrives of the opposite polarity and the coil fires again it will show trace with opposite spark plug polarity. "

well, yes or no

What you write is generally true at certain (slow) speeds, but not necessarily at high speeds (see my graphs and explanation above).


Top of pagePrevious messageNext messageBottom of page Link to this message  By coreywalker on Friday, July 09, 2010 - 11:05 pm:

You guys amaze me, I'm a welder, play with electricity every day. Have no idea what you all are talking about. My T runs like a top with Ron's coils and magneto. I'll keep reading and continue to be confused!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Friday, July 09, 2010 - 11:29 pm:

Corey,

Electrical engineers are crazy - they BELIEVE in the square root of negative numbers.

The rest of us that post here on the subject are brain-dead because we've been shocked in the wrong places too many times. :-)

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Friday, July 09, 2010 - 11:42 pm:

Arnie asked:"What would the trace look like if one was driving at 25 mph rather than a fast guy like you going 46 mph?"

Good question. Some day I'll hook up my 'scope and see what 25 mph looks like. I can't even remember why I did the test I posted. I do remember that it was difficult to manipulate the 'scope and drive at the same time. Next time I think I'll get a helper.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson on Saturday, July 10, 2010 - 12:47 am:

Arnie
From a practical point of view the answer to your question is very simple. When running ANY Model T on the magneto regardless of engine speed when the timer makes contact the polarity of the next magneto current pulse sufficient to fire the coil determines the polarity of the spark to the plug.
Any other esoteric explanation is specious nonsense.
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Saturday, July 10, 2010 - 01:47 am:

Ron said:"When running ANY Model T on the magneto regardless of engine speed when the timer makes contact the polarity of the next magneto current pulse sufficient to fire the coil determines the polarity of the spark to the plug"

This is a true statement. But, as my graph shows above there are situations where the current can't built on the next available voltage pulse. This is because the points have not had time to close in high speed situations. Since the points are open, there is no current, hence the coil doesn't fire.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Saturday, July 10, 2010 - 08:19 am:

Would this work? The idea is to use the inductor to keep the AC from the mag out of the DC circuit. The inductor would probably have to be large.

Neil


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Saturday, July 10, 2010 - 09:15 am:

I don't know whether it would work or not, but it looks to me like anything ever positive out of the left end of the inductor is going to go to ground.

This one works however. Noel Keefer told me about it. The center-tapped inductor is the secondary of a battery charger transformer.



When the output from the mag's field coil goes negative, the lower end of the center-tapped inductor will be positive.

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Saturday, July 10, 2010 - 10:02 am:

Why would you want to do this? Is the intention to make the car perform better?

This entire discussion makes no sense because the end result of the experiment will net a result less satisfactory than a properly tuned unmolested Model T ignition system.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Dufault on Saturday, July 10, 2010 - 10:49 am:

"This entire discussion makes no sense because the end result of the experiment will net a result less satisfactory than a properly tuned unmolested Model T ignition system."

Perhaps the last part of that statement is true, but the humorous back and forth banter and the knowledge disseminated makes for great entertaining and instructional reading!
Thanks ALL!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Saturday, July 10, 2010 - 11:22 am:

Royce, the intention is to provide a fully adjustable spark advance rather than incremental steps as explaned by Ron, such as provided by a distributor, while using all the advantages of the flywheel mag and keeping the original coils.

I have no idea if it would actually help. However, it is fun just to think about.

Neil


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Saturday, July 10, 2010 - 11:24 am:

Going back to Arnie's second post, "The literature states that electrons flow more readily from a hot body to a cold. By making the electrons flow from the center electrode of the spark plug it is said to improve performance."

Given that a rich mixture fires at lower voltage than a lean mixture, maybe part of the need for choking a cold engine is to enable sparking from cold plugs.

Could pre-heated sparkplugs reduce or eliminate the need for choking a cold engine?

rdr
Treading in new thoughts, at least for me.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Saturday, July 10, 2010 - 11:52 am:

Fully adjustable ignition timing is a huge benefit at low engine speeds. It probably prolongs the life of the crankshaft also.

But it is only fully adjustable if filter capacitors are used, unfiltered full-wave DC is still going to have 22.5 degree timing steps - but all of the same polarity.

There is plenty of half-wave output from the field coil to need nothing more than a SCR for rectification and voltage regulation and about 20,000 mfd of capacitance.

I did it. It worked great. I'd do it again if I ever had another T.

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Saturday, July 10, 2010 - 12:03 pm:

If I wanted a better ignition system on a Model T (or any car) I would simply install a modern high performance capacitive discharge system such as an MSD-7AL with a crank trigger. I have done exactly this on my 1967 Mercury Cougar which is powered by a 500+ horsepower bored / stroked 427.

This type of high power ignition does not increase horsepower. It improves cold engine performance in a modified engine like mine. It improves the idle quality with the radical camshaft profile. It allows me to set timing on individual cylinders. It has a rev limiter to prevent engine damage in the event of a midssed shift. I also can install a "valet chip" that limits RPM to 2500 when the car is being driven by the mechanic at the tire store or alignment shop.

Other advantages of higher powered ignition are longer time between tune ups, increased plug life, and better gas mileage.

In conclusion, I again state my opinion:

You could do any of the things mentioned by Arnie and it would have the same effect as swapping the battery cables. In fact, the same improvement could probably be seen by swinging a rubber chicken around as you drive.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Saturday, July 10, 2010 - 02:17 pm:

Royce, the reason we talk about this stuff is because for some of us it is fun to talk about it. I agree with you on a certain level though, for the average guy, the stock T system (well tuned) is fine.

Noel, I like your phase inverter idea. Of course the inverted leg will be diminished by the limits of the inductor (efficiency and possible core saturation e.g.) But something is better than nothing.

I have been accused of "fuzzing" up this thread. Nothing I have presented here seems fuzzy to me, but if I have written anything that anyone doesn't understand or disagrees with me on, let me know and I'll try to straighten it out.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Arnie Johansen on Saturday, July 10, 2010 - 02:56 pm:

Tom:


I do not think you are "fuzzing" up this thread. The only thing fuzzy is my brain!!!

Thank you for providing the trace which shows at 46mph in your vehicle the traces are of one polarity only. That is, it "skips" the opposite polarity at 46 mph while under magneto operation. I would have never guessed that!

I know this post was originally about operation under battery conditions, but I think I have learned more about operation under magneto conditions and thank you for that.

Perhaps if you do another test at a lower speed, Sue could be your co-pilot and operate the scope! It would be interesting to see the three or possible four firings and if at low speed under magneto operation the polarity changes back and forth! Or for that matter just how low a speed one needs to go to get polarity changes if indeed it does ever happen.

Arnie

P.S. Sue, I hope you are not mad at me to suggest you as the co-pilot if Tom ever performs the test. I just think since you were able to do the cross country run, this would be a piece of cake for you! Also you might be the first one in the world to find out just when and if polarity changes occurr. I bet you are really excited about that!!!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Saturday, July 10, 2010 - 03:23 pm:

Arnie, thanks for the kind words. I don't understand the hateful mail I've been getting when all I'm trying to do is help and have fun.

I'm sure Sue would help me. She is my co-pilot in everything. I believe that she is the only person on this planet that loves me more than I love myself! (Well, on second thought, maybe my Mom and maybe my sister.)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Saturday, July 10, 2010 - 04:28 pm:

You guys getting hateful mail? Boy, I feel left out.

Maybe I should post the comparison chart I've made between Ford "Steady by Jerks" ignition and really good ignition, as exemplified by the Atwater-Kent Unisparker of 1911.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dolores Fillman on Saturday, July 10, 2010 - 04:53 pm:

My husband and dad have the electrical and mechanical knowlege, I concern myself mostly with the effects of gravity, :-( and the force with which a moving object impacts either a stationary or other moving object.
BUT, I've been watching this thread with interest, learning what I could, laughing with you guys and measuring the overall length of the thread. It is the longest I've seen.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Dufault on Saturday, July 10, 2010 - 05:02 pm:

You're close....His Eminence, Bruce, had a birthday awhile back....the comments and good wishes about it went on and on and on.......for quite awhile longer than this one


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Saturday, July 10, 2010 - 05:53 pm:

OK Arnie, here are some traces taken at slower speed.

The first one is at about 12 MPH. The blue trace shows the current, and the red shows the voltage. You'll notice that the coil fires on each voltage pulse.

1

The next one is at approx. 25 MPH. Again the coil fires on every pulse.

2

This lasy one is at 31 MPH. At this speed the coil begins to skip. Notice that when the coil skips there is voltage, but no current. (25 ms e.g.)

3

Now mind you, the skipping has nothing to do with how the car runs. Only the first spark really matters. If the engine doesn't fire on the first spark, the second one is probably too late. I have shown these only as a conversation piece. (Notice how I'm all defensive, hoping to stave off the hate-mail).

As a side note, the spark lever is advanced from the "sweet spot". The timer is closing about half-way through the (half) wave cycle.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Arnie Johansen on Saturday, July 10, 2010 - 06:02 pm:

Thank you Tom for going the extra mile! If you are in the Chicago area again, it looks like I owe you another lunch or more! (by the way folks, I should point out that I am frugal and it was only a lunch at McDonalds that Tom got out of me last time!)

I will need time to digest these tracings as I am a mechanical rather than electrical person.

Can I ask one question?? Why were the traces not run on the "sweet spot" but advanced from it?

Arnie

P.S. Was Sue your co-pilot on these runs?

Thanks again for running the traces and helping us all get a better understanding of the Model T Ford ignition!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Arnie Johansen on Saturday, July 10, 2010 - 06:32 pm:

Tom:

Some additional questions (I bet you are tired of hearing from me!)

Do the numerical values on the vertical axis have any meaning? The ones on the right vertical axis seem to be 10x the values on the left vertical axis! My guess, it was just to show the voltage variation?

Is the horizonal axis values in ms accurate?

Did you run your vehicle in high gear during all tests?

Any idea why the current seemed to rise at about the 25ms point in the graph at 25 mph?

Arnie


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Saturday, July 10, 2010 - 07:19 pm:

Arnie, I will answer questions from you or anyone, until we arrive at the truth, or I drop! I am not a cut and run kinda guy.

By the way - anyone is welcome to chime in on this.

I did not set the spark at the "sweet spot" because I wasn't careful. The tests were taken with the motor running, but not driving the car. My laptop battery was dead, so I just did the tests whilst sitting there - it shouldn't make a difference. The first test was ~ 470 RPM the second ~ 940 RPM and the third, ~ 1250 RPM.

The right hand axis is volts/10, the left is amps/100.

The horizontal axis is accurate.

The current is rising at 18, 32, and 40 too. I should have mentioned that the polarity of the current is shown backwards from the voltage to make it easier to see. I did this by turning the amp probe end-for-end (making the primary wire go through the probe the wrong way).

I should have mentioned this from the start. Sorry for the confusion there.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Noel Keefer on Saturday, July 10, 2010 - 11:57 pm:

Tom,
Great visuals of undeniable data that for substantiats all that was correctly stated.
I notice your data is going off screen. This must be the reason we don't see the flat spot on the primary when the voltage potential reaches the point where the plug fires.
The circuit Seth shows I sent to him for fun, and has never been tried, both you and seth caught on to the unknown issue of the inductance. Perhaps a capacitor tuned to just above the RPM we use would work. I have no need to go further with it. I am converting my 1914 over to 12 volts and an alternator. Oh, yeh, the new engine that I just finished making up has a Model A crank. Simple to convert, just takes the usual 10X the time anticipated time to finish!! Also a Chevy 3 speed synchro tranny and a VW carb on an inverted A intake manifold. Next is Model A brakes on the rears.

Royce, What can I say. The info here has been provocative. But, you know, the real truth started to form toward the end of this thread. As someone stsrted "this forum is for discussion by interested parties".

"If your dog don't hunt, stay home"

With respect, almost
Noel


Top of pagePrevious messageNext messageBottom of page Link to this message  By Noel Keefer on Saturday, July 10, 2010 - 11:58 pm:

Fellas,
Several years ago Seth designed a beautiful circuit that no-one either knows about or cares. He starts his T with 4 AA cells and automatically the circuit shifted to a full DC rectified magneto voltage that gives infinte adjustable timing just like a distributer. All this with no battery on board. IE: a hand cranked engine. The batteries will last more than a season!!

He sent me the circuit and a prototype unit in his stylish OAK motif. His workmanship is marvelous!

He spoke about it on this forum and was banished from playing on the same ball field as the rest of us! I admire how much restraint he has shown on this thread. For 5-10 bucks you can drive like a distributor ignition. No more Gypsy timing, jumping by 22.5 degrees. Or as RDR stated "Forward by Jerks"!

Hey, RDR, you did mean the mag timing, didn't you? ;-}

Again,

Respectfully,

Noel


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Sunday, July 11, 2010 - 12:11 am:

Noel, I was just quoting from the "Fast Ford Handbook." or whatever it's called.

There's another book, "What You Think of Me is None of My Business."

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Sunday, July 11, 2010 - 12:14 am:

Back to the original:

In a warm engine, is the center electrode really going to be enough hotter than the ground electrode to matter to electron flow?

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Harris on Sunday, July 11, 2010 - 12:35 am:

But back to the original question about changing spark plug polarity. Before Model T Fords, cars ran on a bank of six 1 1/2 volt dry cell batteries so they got nine volts to power their wooden coils which were very much like Model T coils. The question was "can you change polarity" and the answer is yes so the electricity goes the other way and builds up the other side for a while. Just don't attempt to do it on a magneto equipped car unless you rewire everything. The Model T Ford ignition system is designed to start on D C and run on A C. Yes I know they will start on A C but that is only a Model T with a magneto.

I have stated before on this web site, I changed the polarity of my coils on our 1906 Moline two cylinder touring car regularly in order to not build in a "set" into the points.

With respect to the vibrating coil running on alternating current, it is not running on a c when on battery. It is running on pulsating direct current with the electrons all flowing one way.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Sunday, July 11, 2010 - 01:42 am:

Ralph asked:"In a warm engine, is the center electrode really going to be enough hotter than the ground electrode to matter to electron flow? "

In my opinion, no. With a stock T's low compression, I think the stock system works fine. My only interest in all this is theoretical. My goal in life is to make a stock T run as good as it can (or should). Stock being described as what the Montana 500 rules allow.

Noel said:"I notice your data is going off screen. This must be the reason we don't see the flat spot on the primary when the voltage potential reaches the point where the plug fires."

yeah, could be. I puffed it up so that it was easier to see the mag voltage.

I just noticed something. On the last graph (I called it the lasy one) at about 42ms is an example of a delayed (retarded) spark caused by the timer being advanced from the sweet spot. I also noticed that the timing between cylinders is inaccurate. The first two cylinders at 0ms and 22ms are triggered from the sweet spot. The third at 42 has the timer clearly advanced. I'll bet my timing cover is off-center on this car.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Sunday, July 11, 2010 - 05:30 am:

Tom,

Thank you for going to all the trouble to gather data and post it here. To hell with the haters and the hate mail. I can imagine who they are.

Noel,

Thanks for your comments. A little correction is in order however. The device I sent you uses 4 C cells. I never quite figured out how to do what I did using four AA cells so I gave up and never tried. Perhaps I had become defeated by all the naysayers here. :-)

For those of you with batteries and stock ignition, especially those of you that also run high-compression cylinder heads:

In my opinion, operating on the battery at low engine speeds under load will improve the life of the crankshaft, main bearings, and connecting rod bearings. 22.5 degree wide choices in ignition timing are far from desirable when operating near or below the peak torque speed.

Have a great Sunday.

Seth


Add a Message


This is a private posting area. Only registered users and moderators may post messages here.
Username:  
Password:

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration