Spark plug chart 1960-1973

[moparbob71.2]

Figured I'd post this for everyone. I've been going thru my plugs and this chart is on the back of one package. Not 100% useful ( they show the same plug for 318 and 426) but better than nothing when you're at a swap meet looking at a table full of spark plug numbers.Enjoy.

 

[ocdart]

Interesting, but uncertain of the accuracy. The recommended plug for my '69 Dart Swinger 340 back then was a Champion N9Y.
I know that's a fairly cold plug. I couldn't get Champions to live in my 340 so I went to the equivalent Autolite plug and never had a problem.