Yet another comparison (air-gap carb spacers)

Seems to depend on the engine's requirements. A buddy of mine had a pretty hot 340 with a AG and he tried an open spacer and it didn't like it. I have a mild 408 in my Cuda and tried all three ways, no spacer vs. a 4 hole vs. an open spacer and it liked the open the best. I don't have a dyno test or track time to verify it, just seat of the pants feel so take it as you will.