Okay - Lucy's poly 301 now has an operating Carter WCFB model 2126 vacuum secondary 4 bbl. It came off a 331 hemi and has been bolted to a 392 hemi intake manifold. The carb was kinda rough, but all passegways were cleared out (even pulled the welch plugs) and a rebuild kit was added. I've gotten her to run, but am stuck with a low idle lope/roll - as if the motor has a cam (which it doesn't). I've pulled it apart twice and have done the following: 1) reset float levels 2) reset secondary throttle plates in their bores - they're tight. 3) set the vacuum diapragm to the second adjustment hole to aid in secondary closure. 4) adjusted linkages to get to the factory 10 degree opening of the secondaries at WOT. 5) staked the throttle shafts in thir bores to eliminate freeplay due to wear. None of this has had a significant effect on the roll/lope. Oddly - and this is what has me stumped - if I place two fingers over the secondary venturis and *partially* block the air flow, the motor smooths out. If I block the secondaries entirely - the motor will die. This makes no sense; I've never experienced this and I've rebuilt plenty of carbies. Anybody have insight?