I recently had a similiar issue with my stock '69 Z. I increased the initial timing (from the factory 4 degress BTDC) a bit to obtain a better idle, and in the process adjusted the Holley DZ-4053 carb too.
After that I would often have difficulty starting it when it was hot (it always started instantly when cold), and when I had trouble starting it when it was hot, the only way to get it started was to hold the pedal to the floor and crank for 5 or 6 seconds, as if it were flooded.
Well, it turns out I had not set the idle mixture screws properly (they seem to be very sensitive to even an 1/8th of a turn on my Holley) and it was running way too rich, which was fine for cold starts, but problematic for hot starts. I cleaned out the idle circuit and readjusted the idle mixture screws, and now my hot start problems are gone.
I don't know if Edelbrock carbs are as sensitive as my Holley seems to be to the idle mixture, but you could be running a bit too rich, and that would give you the symptoms you are experiencing, as a rich mixture can cause hot start problems.
I know it's no fun to be in a grocery store parking lot cranking and cranking your classic first generation Camaro while some 17 year old hops in to a '95 Accord next to you and takes off while you're still cranking.