350 sbc runs rough and blows smoke

Put some rags under/along side of the carb and remove the float level sight plugs. Turn the electric fuel pump on, DO NOT crank the engine. Watch for gas flowing out of the sight plugs. Unless you have a switch under the hood, in easy reach, this is better done with a helper.

 

I guess if this is a Quick Fuel carb, I would look to make sure it's not flooding. I had a friend who had one of their 850's and it ran bad and flooded all the time and finally go it fixed. I know I posted about it in another thread but it turned out to be a float hanging on the rear jet extensions, then after fixing that the darn thing flooded another time. I found the float was hanging inside to rear bowl on one of the corners. I replaced it with a Holley brass one and now it has been good since last spring. That is something to look for with Quick Fuels float bowls.

 

Me 2

 

So did the engine run good at one point and then started running rich? I would open up your float bowl sight plugs and turn on your fuel pump and see if the carb is overflowing. I am only suggesting this as it seems like the engine runs as expected with the fuel pump turned off.

 

A new fuel filter is not going to help that issue.

Lowend and others are zeroing in on a timing issue. Timing is "fine" doesn't help diagnose your issue. To start with again - what is your base or initial and total timing, without vacuum advance? Hopefully your using vacuum advance, so is it connected to full time or ported vacuum on the carburetor?

I'm with some others in leaning toward a carburetor issue because of how quickly you're fouling the plugs. You said the fuel was set for 7 psi. Is that set through a regulator or is that what the pump is supposed to be set for? If you need to know how to check float levels or check for a stuck float, let us know, someone will chime in. If you need help with reading and adjusting timing, we can help with that also.

 

does the carb have a choke and is it operating correctly

 

I had a Speed Demon carb (w/4 corner adjustments) years ago that I took out of the box and ran it. It ran great on start up and then about 3/4 of a mile out from my driveway it started flooding and ran rich. I limped it back home and it died on the carport. Took the carb back off and loosened the bowls to find that it was chunked full of aluminum cuttings from machining. A chip had found its way in the needle and seat and was hanging a float open....cleaned all of that out and it ran okay. But customer service told me that it was my fault and those chips were from my new fuel lines and filter...LOL