[Tommy]

Basically I agree with Ed. But perhaps my experience will be informative. . . My Cobra had a custom built 408 Windsor configured for track use. It used Autolite 3932 cold racing plugs. With those plugs and the absence of a choke on the carburetor I had to use extra fuel at start up to keep it running until it warmed up a bit. That would occasionally cause it to foul a plug. I live near an open road so as soon as I could I would run it up to 4000 RPM or so and keep it there until the fouled plug cleared up (a minute or less). Once it got warmed up it did not foul the plugs. . . So I suggest two things in addition to what Ed said. First, take a look at the carburetor after it has warmed up to be sure the choke is fully open. Second, when you have an opportunity to safely run the engine at higher RPM for a minute or so, take it. Then check your plugs to see how they are doing.