this may sound stupid, but while i was chasing down a heat soak issues on my eddy 1411 carb on a dual plane intake(Eddy CH4B on a 440), i installed a 4-hole 1" spacer....to my surprise my idle and low end was now tunable, and i completely solved my pig rich issues.
i'm thinking along the lines that a 4bbl carb on a big hole of an intake doesn't give that good a signal to the barrels of the carb, but i could tell right on startup that stoopid 4-hole spacer made a HUGE difference....it also cured my off-idle stumble!!