NGK Spark Plugs..

[Keith Tedford]

I have one box of the old AC43N plugs left and will keep them for the COPO engine. I'll have to try the NGK plugs from now on in the 396. I used them years ago in my snowmobiles when the Bosch plugs just didn't work. We didn't need to carry spare plugs after that.

[67 442]

I used NGK plugs in my 67 442 and it was night and day compared to the AC plugs I was using. They really woke up the motor. Very inexpensive hp increase.

[JimL78]

If anyone is looking for pretty near an exact copy of the AC 43N in NGK the number is B7ES. I've been running them for a couple of years and have had terrific luck with them.
Jim

[PxTx]

I too have had good luck with NGK.

I have also done a bunch of research on how plugs are made. Champion is sort of unique in manufacturing. If you've got any laying around, you can actually unthread the metal plug connector form the porcelain. You can then see the talc, spring and resistor (or not depending). Kinda neat to see the anatomy of a spark plug.

I would suspect that if Champion is making AC plugs, they would be making them to AC spec, and not necessarily their own. I bet you can still unthread a Champion end, while the AC plugs probably are assembled as they always were. Not saying anything about the quality of the old vs new other than they are not equivalents of each other just because Champion makes both.