The old pump gasoline that was 100% gasoline or new non oxygenated fuels are stoichiometric at about 14.7:1. Now we add ethanol to the gasoline and we add O2 molecules to the mix. Watch Matt with GT350 Garage videos on fuel as he does a good job of explaining the whole deal. E100 is stiochiometric around 10:1. So an E10 fuel is stiochiometric about 14.1:1. This is commonly available pump gas these days. Power fuel ratio should be 11.5:1 to 12:1.
When I looked at the Edelbrock AVS2 650 calibration (jets and metering rods) as compared to the older Performer 600 calibration, they appear to be much richer. It was after watching Matt explain fuel ratios and alcohols that my understanding came. Edelbrock is setting the factory calibration with oxygenated fuels in mind. Edelbrock tech recommended that when installing the AVS2 annular boosters in the primaries of my Performer 600, to start with the AVS2 factory calibration and tune from there.