Hey pete, that's interesting, but I have no idea what you mean by "really only work" - what is the advantage of the iridium that one side will miss out on?
Thanks!
Iridium spark plugs have a precious metal tip that can get much hotter before it melts. Heat encourages the electrons to literally jump off the tip and go towards the ground electrode. If you are old enough to remember tubes in your TV set, you will recall that they had a hot cathode that emitted electrons towards the positively charged plate, and that's the problem with a dual output coil. Only the negative wire actually has any electrons to emit from the hot tip. The electrons are negative and they are attracted to a positive voltage. So, the plug with the positive wire does not have any electrons to take advantage of that hot precious metal tip.
Also, because the electrons flow from the hot tip to the cold ground electrode, the negative wire plug is more efficient, like, 40% more efficient and that is the main reason that modern wasted spark systems have a "high performance" coil in the first place. To overcome the positive wire deficiency.
Knowing this, if you could determine which wire is the negative wire, you just install an Iridium plug on that wire and install an ordinary plug on the positive wire, thus saving the cost of one Iridium plug.
Ford motor recognizes this anomaly and they supply two kinds of plugs in their cars that have a wasted spark system. One of the plugs has the precious metal on the tip for the negative wire, and the other plug has the precious metal on the ground electrode, although the negative wire plug is still mote efficient because the tip gets hotter than the ground electrode.
You can also buy double platinum plugs that have the precious metal on both the tip and the ground electrode.
One of the ironies here is that the Iridium plugs work better on a stock points system because both coils produce a negative voltage, although the benefit is questionable because the stock points coils produce such a weak voltage that there is not enough current flow (available electrons) to make a difference.
Now, on the 277 RePhase PAMCO setup there are two coils and they are both negative, so Iridiums on a 277 is the way to go. Perhaps another reason to do the conversion!
I had though about making a dual sensor PAMCO for the standard 360 engine if there was enough interest and understanding of the potential benefit.
Of course, the other argument is that high performance coils, like the 17-6903 "Ultimate" coil produce more than enough voltage and current flow that it doesn't matter about the plug wire polarity, and that's the argument that I believe in.
I find spark plugs fascinating. There are people who get a Masters or Doctorate degree to study and improve spark plugs. Same with golf balls and baseball bats.