Thank You! I don't know much about reading plugs. However when I pulled my 340 out of the 66 satellite (points distributor) I switched the electronic when I shoved it in my duster same transmission same gear then when I pulled one out they were all kind of nasty black looking rich. Then again A friend of mine adjusted it till it ran the sending unit was clogged it was an old fuel tank I put in a new fuel tank new sending unit new fuel lines and didn't reset the carburetor adjustments that's probably what happened. Anyhow, Back to the Nitrous!