1979 Lincoln Mark V running too rich


I just bought a 1979 Lincoln Mark V that’s running too rich. The spark plugs are all carboned up. I replaced the spark plugs, wires, rotor and cap and it’s running the same. The EGR valve seems to be working but I’m not positive. The car was sitting probably for long periods, it only has 21,366. I didn’t realize the car has a O2 sensor, so maybe that’s causing it or the carburetor needs a rebuild. Any help would be appreciated. The engine sounded great after I installed new plugs until they carboned up within a few minutes of running.


The carburetor needs to be rebuilt , and you need to add additives to the fuel these cars run terrible on the gas they run on today.


Thanks for the reply, I really appreciate it. I did rebuild the carburetor after my first post. It’s running nice now, both gaskets below the carburetor were in pretty bad shape. You could see carbon deposits on them, so they were leaking and the power valve I think was bad. There’s no more carbon deposits on the plugs or black smoke coming out of the tail pipe. I’ll try adding an additive, thanks for that tip!