Cars driven on the street definitely need vac advance and setting it up correctly would solve a lot of peoples cooling issues. When you are running in a lean condition (idle or very light throttle cruising) you need way more advance than you would expect. For years I had my car set up with no vac advance because the muscle car guys say "you dont need it" - well that is true if you are at WOT all the time but not if you drive your car around. This car was chronically hot and could not idle in traffic for more than a few minutes. You could hear the coolant boiling when you turned it off etc. By simply hooking up the vac and making some adjustments so that it was working at idle the problem is solved - it can idle indefinitely and will never get much over the thermostat rating. This also helps a car that runs hot at a steady light cruise on the highway. From what I have researched, the ported vacuum was implemented in the 1970s as an early emissions move. The end effect was increasing the heat in the manifolds as a post-engine afterburner of exhaust prior to developing catalytic converters. The same car I mentioned with no vac advance heated the engine compartments and hood hinges to the point you could not touch them for this reason. The car now has about 13 deg initial, about 30 deg at idle with vac advance, and over 50 degrees going down the highway with the throttle just cracked open.
