Questions and Answers
Black Spark Plugs
Q. Vince, I have a 1977 Lincoln Continental Mark V. It has a 460 motor, automatic, carburetor, all power options, with 100,000 kilometers on it. I drive it approximately 3,000 kilometers every year, driving it only in the summer.
Recently I changed the plugs. I noticed that after a couple hundred kilometers, four of the plugs on the drivers side (plugs 5, 6, 7, 8) had a buildup of black soot on them. The other four were perfect. I went back to the parts store, but they assured me they were the correct plugs, but I bought a new set anyway. I verified the gap, metered the plug wires but again after a 100 kilometers, the same four plugs were fouled again. Any thoughts or suggestions would be appreciated.
Thanks...
A. The most common cause of this is a mis-adjusted carburetor. If I remember correctly, that has a Holley four barrel. I would recommend having the carburetor adjusted using a four gas analyzer. Also If you are using Champion plugs, go to Motorcraft, it does make a difference.
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