Interesting find... I'll show some spark plugs!
 

Actually, I am very intrigued and amazed at my findings. I always thought that the leading coil would be tapped in the center and that both plugs would fire Positive. I changed out my spark plugs last night and came to an amazing find. The Leading coil is NOT center tapped so one leading plug fires Negative and the other fires Positive. See the attached picture!

In the above picture, you can see that the ground electrode on one spark plug is barely worn but the positive side is burned to a crisp, The other spark plug is exactly opposite.

This means you could, in theory, swap your leading plug wires between plug changes and extend the life of your spark plugs.

step away from the Back of the car...you are inhaling toxic fumes.

https://cimg1.ibsrv.net/gimg/www.rx7...ea280793f5.png

... honestly I actually have noticed a difference in the front and rear leading plug wear but I never read anything into it...

jjwalker is correct.

Think TIG welding. Electrode is negative because when it comes to electron flow, more heat/damage happens to the material they flow to, in a much greater degree, than the material they flow from. When TIG welding aluminum, you turn the welder on reverse polarity (electrode positive) to ball the end of the electrode. This is for AC welding of aluminum.

Aren't nearly all wasted coils of this design?

I just did some searching, and google confirms that yes, this is true.

I didn't know until I took my plugs out and looked at them and thought "Hey, wait a second!".

I saw this thread when I was at work, but yes. All waste coils are of this design.

https://repairguide.autozone.com/zne...5280268e03.jpg

Interesting observation JJ, I'd have never guessed. Now I'm curious - what are the implications of disconnecting one of the plug wires on the circuit? I suspect the other (connected) plug will fire, but does this stress the coil?

The coil will fire weakly and yes it stresses the coil.

should we start rotating are plugs to even the wear? lol

Yes, you should.

I mentioned that in my second post. :nod:

You just need to swap the wires, you can leave the plugs in

Uhh... I dunno about you, but I'd rather switch the plugs than the wires.

Why? Don't both leading plugs fire at the same time all the time?

So you take the plugs out with the wires still on them? I'd like to see that and, why?

rx7
 

They don't fire at the same time do they?

L1 and L2 fire at the same time. Is it safe to say the trailing wear evenly, considering it's on a toggle?

Both leading plugs fire at the same time, swapping the leading wires isn't going to hurt your car. Leave the trailings alone.