Hmmmmm- - - - -I posted another comment, but the forum ate it, I guess. Check the power valve in the carburetor. If you're running a Rochester B they're notorious about the vacuum piston sticking and holding the power valve in the full rich position. That makes for lousy gas mileage, rough running, and fuel-fouled spark plugs.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!