Quote: It is still my general belief that my engine is running almost exclusively on the transition at highway cruise (22" vacuum) but it is not clear to me why the fuel mixture gets so unstable. Perhaps there is another, non-carb, issue with the engine. I'm pretty confident the ignition is in good shape now (Mopar Distributor, 6AL-2 box).
Dave, perhaps a non-carb issue yes, but I wonder if, after changing your e-bleed configuration, your fuel level is even with one of the upper e-bleeds at light cruise, causing it to alternately suck air, suck fuel, etc. as the fuel level slightly fluctuates. Easy to test - just raise or lower the float level a tad and go for a ride.
Based on what you've said, I agree that you're cruising mostly on the t-slots, but I'd be surprised if the mains weren't working enough for this scenario to play out, IF the fuel level was just right...or in your case, just wrong, in comparison to the upper e-bleeds.
