Classic/Antique Car Repair: 1948 Mercury Flathead 239 V8, Ford Flathead rich engine condition

Question
My engine starts and runs but it runs very rich as evidenced by black residue coming out of exhaust pipe unto floor and spark plugs sooting and blackened.

I have tried adjusting the two barrel carburetor ( two screws) but when I screw them all the way in or out the engine does not seem to change operation.   I have screwed them both all the way in which I assume is as lean as it can get.

Any advice will be appreciated.

Answer
Hello Paul,

Going for the most common symptom first, your problem sounds like a carb. float set too high or another internal carburetor condition. If you haven't done so recently, thoroughly clean the carburetor both inside and out,and put in a carburetor kit. As part of the carburetor rebuild, make sure to clean out all the internal passages and take care to make sure all adjustments are correct. As the most common cause of the condition you describe is dirt, I like to replace the fuel filter at the same time if it hasn't been done recently also.

If all is right with the gods, this should solve your over-rich condition. If not, you've just established a good baseline for additional diagnosis. Write me if this doesn't work and we'll take the next step on your old flattie!

Good luck,

Bob