timing and vacuum

[john_nowosacki@xxxx]

Question for the mechanics in the group.
Can ignition timing (distributor position) have an effect on measured intake manifold vacuum?
My 57 is running ragged after replacing the two silly Holley 2-barrels with rebuilt original WCFB's.
I know distributor may have been bumped over the winter, but I'm having trouble locating either a mark on the balancer or markings on the metal tab that used to have 0-5-10 (?) or 5-0-5 (?) labeling.
I'm only measuring 10-12" of vacuum, and I think it should be closer to 20".
Car starts ok, runs at a fast idle, but seems to be running on less than all 8 at low idle.
Also, while I have your attention, exhaust gas from the passenger side is significantly warmer (at tailpipe) than drivers side. (no crossover tube in exhaust system, and same volume of air coming out each side).
It was a long winter, so I changed (too) many things without being able to restart after each to check progress. (pulled plugs to put new valve cover gaskets on, pulled old Holleys to put on freshly rebuilt WCFB's, relocated coil and wires to proper position to make room for air cleaners, etc.)
Any help/suggestions appreciated.
If timing is too far advanced, and cylinders fire perhaps a tiny fraction before intake valves are closed all the way, I assume that would reduce vacuum, or am I over complicating things and the WCFB's are the most likely culprit?
It should be simpler than this. It's just fuel and air in the right ratio at the right time!
John