[wolf k]

^ Initially, I had to set combined base and vacuum advance at idle to 30 deg BTDC (vacuum advance is manifold sourced not ported) just to allow the engine to idle with the throttle set with the transition slots correctly exposed.
After increasing the valve lash from .014 to .020 on the intake valves and .018 to .020 on the exhaust valves I can now idle down the engine to 800 with the same distributor settings. I am now able to disconnect vacuum advance at idle to see what the base timing is and it is around 6 BTDC.
However, I will most likely leave vacuum advance manifold sourced, as it runs well off idle the way it is. I have to deduce that the engine builder has lightened the vacuum canister spring as much as possible to get that much vacuum advance at idle.