MSD polarity tech question

[Dragsinger]

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?

[FED 387]

Larry sent u an email. Dick

[Dragsinger]

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.

[Adger Smith]

Larry, Do you have a scope?