One thing I learned from the docs, I am 95% sure my vacuum can is connected to ported vacuum and not manifold vacuum. My vacuum line comes from the can, to the front of my Qjet to the port above the right adjustment screw.
I "think" this location is the original factory connection and from the reading this was for emissions. While this is the factory distributor vacuum can source, it is not a proper source?? Gee I hope I read that right!
Edit:
yes, it does make a difference - the clearly reacts to manifold Vacuum as apposed to the connect I have it on the Carb that is ported. When on the Carb ported Vacuum, there isn't a difference when I disconnect it. When I moved to manifold vacuum, I gained roughly 150 RPMs and when I disconnect it I bounce back to my idle set speed from the carb's ported vacuum.
I also read here on this web page basically the same, distributor should use full manifold vacuum:
Everything You Wanted to Know About Vacuum Advance and Ignition Timing
Edit 2:
Man, there is so much on Manifold vs Port Cab Vacuum ... talk about having a line in the sand with groups of people on either side!