Classic/Antique Car Repair: 56 tbird

Question
Hi. Just new owner of 56 tbird 312 holley 4 barrel. Car was running ok. Has 2k miles. recent partial rebuid from someone. I noticed now after car warms up it starts to run like missing cylinder. when i pull  3rd wire on distrubtor( the  third cylinder) the car  doesnt change and no noise when i recoonect wire into distrutor cap. Do u think it is rotor cap, points and condenser. I pulled plugs and they are all the same black covered dust. engine bouncing really  alot at idle. your thoughts

Answer
The most likely thing that comes to mind is a defective power valve in the carburetor. This is a common problem with Holley carburetors. The black sooty powder on the plugs tells me the engine is running rich and a defective power valve will cause the engine to run rich. We are lot of this with these carburetors in the shop. I run a carburetor shop specializing in old cars here in Fort Myers Florida.