Re: Idle Vacuum
Adding IDLE timing would help bring idle vacuum up a bit.
That cam would want me to use 12/14 degrees if INITIAL timing, and set the degrees stop of the vacuum advance to add 10 degrees more timing, on full manifold vacuum, to give 24 degrees of IDLE timing.
This should help to get a couple more in/hg of vacuum, and make the carb adjustment easier.
You might also have another issue on the carb. To find this info, you will need to pull the carb off the manifold and physically look at the idle transfer slots and how far they are open. This gets a little specific, but I will keep it simple.
If you look at the primary throttle plates and where they sit at idle settings, choke off, you will see on the throttle bore, a hole below the plate, and up a bit, a slot, partly open under the plates. This slot is responsible for the just off idle fuel transfer from idle to acceleration, and is the first system in the carb to "hit" as acceleration is done. If the slot is too far open, the fuel that should be held in suspension in the slot will be used for idle, because the throttle plates will be idling too far open.
Now, timing at idle will effect just where these plates sit in the throttle bores at idle, and if too far exposed, with the plates open too far, idle and off idle vacuum is lowered, causing more issues.
Now, pulling the carb on and off the manifold ain't fun. I suggest puling the carb just once, and when off, use the idle speed screw to set the throttle plates so they only expose the idle transfer slots the required .020 inch distance. Then, use a scribe to make a line on the throttle bore to mark the ABOVE the throttle plate position, so it can be seen from the top of the carb. This will help in not forcing the carb removal to check the idle transfer slots as you progress along in getting it dialed in right.
Once the idle timing is dialed in, and the carb in correct idle plate position attitude, then, see what you have for idle vacuum.