Dave; all I can tell you is that I have had three carburated Mopars (two currently owned) within last few years. All three, with 10% ethanol required gas down the carb after sitting more than three days. My Power Wagon had the Edelbrock 1406 and then a Thermoquad and no change. After the Thermoquad swap I filled tank with E free 89 octane and was surprised still no change. My others were Aspen E58 with TQ and the Diplomat use to have Quickfuel carb then I went with EFI.

I can't explain why I can only tell you same thing with the three and they otherwise ran/run very well. I will say, looking back, I kind of wish I had installed an electric pump instead of spending the money and seen how that worked first but turning the key and having my Diplomat start right up after two weeks of sitting sometimes (which I really try not to do often) is really nice.