Manifold Vacuum Experiment

Oh I need to come back and add this. While not what I would call a "problem" it has exhibited a rich condition at idle. Stinky exhaust and such, which is indicative of not enough initial timing.....even though I've had it as high as about 25-28 degrees. That just shows that it obviously wants more. The carburetor is only a 650 on a Ford 400 engine, so I hardly think it's too much carburetor. Pretty sure that's timing related. I plan to find out.
interesting: a little off subject , but how much vacuum is too much on a r/b hotrod ???
I `m running full vacuum , has recently gone up to about 15", (think my rings have finally seated???) has been around 4 forever, sure stops oil leaks !!
Asking from u guys who probly know ...

sorry for buttin in rusty...