I will disagree with many of the posters to state you HAVE and DO need to have have vacuum at idle! (CropDusterMan, you are describing ported vacuum, which is different, ...more on that later)

The dizzy hose should be connected to manifold vacuum, not ported vacuum, due to the fact that the fuel/air mixture is leaner at idle and therefore 'needs to have the fire lit' sooner. The vacuum to the dizzy provides a timing advance for normal operation at idle. Same condition occurs at steady highway speeds where you also have lean mixtures and high vacuum.

For timing at idle during tuning, disconnect the vacuum hose at the dizzy to disable the advance that otherwise NEEDS to be present!

The theories regarding ported advance were ill-thought-out when emission control was coming into awareness (1970's) and the idea was used to raise the engine temperatures by leaning out the fuel/air ratios and causing the engines to run hotter and (in a way) more emissions-free.

I have not recently read any of the referenced articles, but I believe I have read them or similar ones in the past. However, there are many articles that support my statements and if you take the time to read them, I believe you will agree with what I have just said.

For the benefit of those that may not know, ported vacuum comes basically from the carb above the butterflies and manifold vacuum comes from below the butterflies. Therefore, with ported vacuum, at idle and the butterflies closed, there would be basically NO vacuum at the port. At high RPMS, when the butterflies are open there would be high vacuum. Manifold vacuum is high at idle and at steady cruise speeds. When you open up the butterflies, manifold vacuum drops. In the mid-60's manifold vacuum was the proper source of dizzy vacuum.

In order to be brief, I have left a few things out. I can elaborate if anyone is interested, and you still may wish to disagree with what I have said, but that is OK because there is a lot of confusing info out there.

Personally, though, I don't plan to reconfigure my dizzy vacuum based on using a ported arrangement, although I can by moving one vacuum line on the carb over.