I drove it today and it ran significantly better than with the old distributor that had either had the pickup wires reversed, or maybe an internal issue causing it to reverse polarity, if that's possible. When Googling, I found the following in a different forum that I found interesting:
Getting the pickup wire polarity wrong, reversed on an MSD setup is worth 20 to 30 full degrees difference, NOT 4 degrees.
I see all sorts of ignition systems every day that people take off and send in, saying there is a problem, and, there usually is. The largest issue I see in timing and rotor phase is the reversed polarity magnetic pickup.
Try this simple test, look at the timing your engine has, with a regular light, or dial back light with the dial back feature off, and record the timing. We can use 12 deg/BTDC as the example. Then, shut the engine down and rotate it using the balancer bolt to your previously recorded timing (our example 12 degrees) to firing number 1 cylinder. Now, mark the distributor body at the number 1 cylinder wire, and pull the cap off. What you should find is a rotor that is very close to centered on that wire terminal. If you have a vacuum advance, it sill ge offset a very slight distance, not more than the width of the rotor blade itself.
IF the rotor ISN'T pointing to a specific terminal, and is somewhere between terminals, then either the magnetic pickup wires are reversed, the magnet is backwards, or, both. Reversing the wires, and/or magnet should bring the rotor back to where it should be, aimed at the wire terminal, not offset significantly from it.
