I've read on another web site (and believe it now that I have an edelbrock) that because the fuel bowls are on the smallish side, evaporation/drain off happens after sitting.
If I leave mine for more than a week, I have to crank it to get the fuel back up to the carb. Anything inside of a week, and it fires right up.
Everything on my engine is less than 3k miles old, and I have no fuel leaks so perhaps it has something to do with the vented gas cap.
Good luck!
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