Very rich running is often caused by a weak ignition.

However, if the vehicle is equiped with a Rochester "B", very rich running is normally caused by warped castings which creates an internal vacuum leak resulting in the power valve always being open.

However, the white tailpipe which many of us knew from childhood to be an indication of a well-tuned engine actually was lead deposits inside the tailpipe. The tailpipe of a vehicle running todays no-lead fuel is black. However, it should not be "sooty".

If the engine is excessively rich, an observer behind the vehicle might guess you are "fogging" for mosquitos.

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop