engine not producing enough vacuum

Good find. On the carbs - they are typically slow opening, and smooth enough that you may not feel them coming on. Take a small piece of wire (like a few strands of copper from a 16gage wire) and wrap them around the shaft tight enough that they can't fall off but lose enough to slide easilly, and keep them up against where the rod goes up into the vacuum pod base. Leave enough length for the wire to contact the sides of the vacuum pod passage the rod passes through. Then drive the car.... The carbs - if they open - will force the wire down the rod a little. Then when you look you'll see the wire has moved. Or replace the springs in the vacuum pods with the light purple springs from Holley. Also make sure the base plate gaskets are not keeping the outbaords from opening very much. If they are not placed properly they can hang up the throttle plates.