[Geary L. Sarno]

Hey guys - Thanks for the feedback.
Another related question. My Edelbrock manual states that 13:1 fuel/air ratio is the best for wide open throttle operation. On the dyno my ratio was 15.6:1 for a wide range and that's where the FE made the best power. When my secondaries started to open the ratio dropped to 13.6 to one and the power/torque curves fell in a similar manner. I'm running dual Edelbrock 600's (1405's) on a 1967 Shelby GT500 intake. I think the problem relates to air speed/volume through the secondaries in the dual carb setup.
My reasoning is that the primaries will supply all required air up to the point where the vacuum demand starts to open the secondaries. The carbs are designed to provide fuel/air through the secondaries based on feeding 100% of the vacuum over what the primaries can support. In this case the carbs would see 100% of the vacuum, but each set of secondaries would provide 50%. Would this reduced air volume contribute to the richness.
If air pressure rises in a geometric curve would 50% volume yield a less than 50% vacuum operated secondary air-plate opening because of reduced speed. - Aggressor