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!

"O say, does that star spangled banner yet wave? Oer the land of the free and the home of the brave?" It does at my house! God bless America!