Holley 670 SA tuning with wideband

The thing with secondaries..........this is to allow some air in instead of through the primaries, so that the primary butterflies will be further closed at the same idle speed. This is to keep the idle transfer slots in proper position with a hotter cam, which otherwise, would require the primary blades to be too far open.

Years ago, some used to preach drilling small holes in the primary blades

Also, get your timing and advance curve "settled" before you screw with carburetion