In recent years the MSD trigger polarity has received some attention. In the "olden days," it was never considered.

For this question, we are talking about an analog MSD 6AL control.

I do understand that for the analog controller, the most retarded timing is the correct polarity. Since the subject began getting attention I have checked a number of 6AL and 7AL analog controllers and so far, each had the correct polarity when the wires connected "color to color" [green to green, purple to purple]

When the colors are swapped, [green to purple] the timing advances about 5 degrees.

Now the question;

Why does the wrong polarity advance the timing? It is as if the controller is predicting the future

Does the control box, when polarity is correct, have that much signal delay? [about 5 degrees]

Anyone know the truth?

In the digital world it would be rising vs. falling edge. Not sure of the analog world though.

Typically a lot of analog circuits that are fed from a very low voltage (typical of a vr-style setup like an MSD cam or crank trigger at cranking rpm's) they need to amplify that signal A LOT! It turns a lowly little sine wave signal into what looks like a square wave signal (in the audio world this is simply a LOT of distortion!).

Maybe that is why the timing will change slightly when swapping the wires around. I can't say for sure though.

the signal is either triggered at the leading edge of the wheel magnet [incorrect polarity] or the trailing edge of the wheel magnet, [correct polarity] thus, the difference in timing.

The analog controller is designed to process the trailing edge signal.

How are the north/south poles on those magnets orientated?

Mike, the answer may be here

http://www.useasydocs.com/theory/pickups.htm

I think the south pole is outward.

Edit: this is from an MSD tech.

"The MSD needs to see the rising edge of the signal. (south pole oriented)"