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Actually, greendragon, the coils do touch together. Most ignition coils are 2 differently wound separate coils. They're connected together in this case, as to be single coils in series around a common core or what is called an autotransformer. The common point is the neg terminal in the schematics referenced.

really? humm, i need to call the school and tell them they are teaching that wrong then.

Not necessarily. There are mentions where the secondary is case connected to ground directly and they are separate. The point being that there has to be a connection on both ends of both coils. The autotransformer method apparently is the one having some advantage since that seems to be the most common.

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My previous research on this subject revealed that a coil will run either way, but if you do not hook up the polarities the right way, the resulting spark will be weaker.

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Agreed.

The question is back to approximately JWs original-- on a universal coil supposedly not polarity dependent, how does one know the proper connection. Using the schematic above for example, on a neg ground car with neg terminal being ground -- as far as the spark is concerned only the secondary (blue winding) is in play and the primary winding is in effect by itself.

However, if the conventional wisdom is followed and the pos terminal is now ground in a pos ground car, then both coils are now in series as far as the spark is concerned. This could either add to the overall voltage or subtract, depending on the direction of the primary coil winding. That connection also determines whether the spark jumps from the electrode to ground (good) or the reverse (bad).

Another question is on a universal coil, are they actually manufactured & connected this way or is that one of the few cases mentioned where the secondary is separate and only between the tower and case. I know they still have the + & - labels but without a meter to check, how would you know universal if you had several on a shelf. Anyone have one to check? I think most of us have seen illustrations of the method using the pencil lead to ensure the spark originates at the wire, but aside from that, is there any other way to tell using something in the way of test equip most would have. JW mentioned a milliamp meter but I'm not quite following that method.

Am I missing something here? Seems like a lot of discussion on something pretty basic. The only significant differences in a "universal" coil would be in the physical configuration of the terminals and perhaps canister size. On the primary (low voltage) side, the (+) goes to the distributor assuming the car is still positive ground, and the (-) goes to the ignition switch. The high voltage lead of course goes to the center of the distributor.

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My two cents worth. The above is absolutely the way it is. It is called an autotransformer but not necessarily because it is used in an auto. Has more to do with the fact that the primary and secondary windings are connected in series with one another.

Never underestimate the wealth of information that is available in the Literature and Manual archive here on the website:

Packard Ignition Service Training Manual

https://packardinfo.com/xoops/html/modules/article/view.article.php?46

This should help a out anyone trying to understand and troubleshoot the Ignition system on their Packard.

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That statement is partially true. The primary and secondary windings are different. The rest of the statement is in error. one end of the primary winding is connected to the voltage source and the other to the distributer points (small wires) but the secondary is where the high tension wire (large wire) to the distributer cap center.

Okay, here I go one more time (just couldn't leave it alone). If the new universal coils are marked so that the positive marked (+) terminal is for the source (switch) and the negative marked (-) terminal is for the distributor, then there is no problem regarding the vehicle's battery ground, if connections are made according to these terminal markings. If this is not the care, then we are back to trying to determine which terminal is to the primary winding.

Regarding my comments about using a meter to check for secondary output. It was a Sun Equipment instrument and I believe one knob setting was marked "Secondary Resistance". We used this setting with one of the leads on the spark plug terminal and the other on ground (vehicle ground dependent, of course) to check for faulty high tension leads (spark plug wires) with the engine running. The test could also be used for other trouble shooting purposes like coil leads hooked-up backwards.