This may be a stupid question and if so forgive my ignorance, I'm still learning. But is the vacuum advance on a distributor supposed to give ANY advance at idle? Not according to the article below....I set my timing at 10 BTDC without the advance connected but once connected again it goes up to (I'd guess) 20 or more. I noticed that before but I didn't really think much of it. If that is in fact too high then I could adjust the timing WITH the hose connected against the manual instructions (My vacuum cannister doesn't appear adjustable). Someone tell me.
http://www.gassavers.org/article/vacuum_timing_and_fuel_economy_in_non_computer_assisted_engines.html
Yes you should have vacuum advance at idle. What you have sounds normal to me.
it must be set with the hose off and plugged. 8-14 deg intial timing should be fine.. it should go to anywere between 18-26 with the line connected.