Stop in for a cup of coffee

I am trying to figure out if I am doing the right thing with my timing. I have 18° at idle with vacuum advance disconnected and plugged. 36° or 38° at 2000rpm if I remember correctly. But the vacuum advance is connected to manifold vacuum as the 660's have no carbureted vacuum ports. So I wonder what the vacuum advance is doing to the timing in this set up. FWIW, I have an MSD Pro Billet ready to run distributor.