Black soot out of exhaust pipe

slantsixdan said
You'd probably tell us if the car was blowing clouds of black smoke, so I'm guessing it's not. Keep in mind the tailpipe will be black and sooty on any car running on unleaded gasoline and not equipped with a catalytic converter (and many catalyst-equipped cars will also have sooty tailpipes, too). You very well may have no problem at all. If your fuel economy is normal and the spark plugs aren't turning black and sooty, there's probably nothing to worry about.

If you are in fact blowing clouds of black smoke or putting black skid marks on the driveway under the tailpipe, then more detail, please. What year is the engine, and how many miles are on it? What kind of carburetor is on it? "1bbl carb (rebuilt)" means...what? An original carb you rebuilt? A "remanufactured" unit from a parts store? How easy or difficult is the engine to start from cold, and how well does it run immediately after a cold start?

Good points Dan. No, the car is not billowing black smoke, the output looks normal and no deposits on the driveway. It's a stock Holley car which I rebuilt. The spark plugs are burning normal and are not black. Everything inside was clean as a whistle. Fuel economy is ok and it runs well even when cold. The engine was "rebuilt" shortly before I got it. Since it doesn't leak or sound bad I have to assume it really was rebuilt. It's also pretty clean at the valve train. I had an old Valiant in the 70's and I don't recall the tailpipe looking black like this one.