I have a 350sbc in my model a. I'm running the middle two carbs on a 6x2 intake. At idle the driver side of the block does not seem to be firing. When I hit the accelerator pedal and get the rpm's up the driver side fires but pops and carries on with a little black smoke too. Today I tried to find the problem by process of elimination. I tightened the intake manifold bolts, mounting bolts on all 6 carbs, rebuilt the two middle carbs, replaced the plugs, replaced the points, rotor and distributor cap. Shot around the intake with carb cleaner to look for vacuum leaks too Still runs the same... Driver side not firing at idle...but kicks in when rpm's are up. Anyone have any suggestions what else I could look for.