One carb not drawing-what's up?

[Gaz64]

Jon,

Try this:

Back out the throttle speed screw for the carb for cylinders 1 & 2.

Place each cylinder in turn at BDC of the inlet stroke.

Use your leakdown tester to inflate the cylinder with low pressure say 10psi.

With the inlet valve open and the carb butterfly closed, you should only hear a tiny loss through the "closed" butterfly and the idle circuit.

If you hear loss through the oil cap, the intake gasket has been sucked in from under the manifold. This would then explain your low airflow measurements for 1 & 2 and associated misfiring.