Quote Originally Posted by knightrider View Post
I was reading that you recommend hooking the vacuum advance to full manifold vacuum. Is this correct for non-ECU control timing?
Yes, I almost always recommend "full manifold vacuum" for vacuum advance distributors. However, sometimes a radical camshaft can fluctuate the manifold vacuum too much, and exacerbate an erratic idle. Of course, the entire distributor centrifugal and vacuum advance curve needs to be properly modified. Another benefit of EFI (easily programmed fuel & ignition curves).

I thought vacuum advance was for cruise only, for better fuel economy.
Vacuum advance should be connected to full manifold vacuum; not ported.
8°-12° of vacuum advance is the typical limit (some canisters are adjustable).
The (ported) timed spark port is only for emissions/EGR engines (LINK).

Could running full vacuum at idle cause the engine to run on when switched off?
No, it actually helps prevent dieseling/run-on: http://www.badasscars.com/index.cfm/...prod/prd94.htm (Read 4th paragraph.)