Hard starting when the engine is warm

Hi everyone,I'm a new member and I need help.I bought a 1978 correct craft mustang17 off this website and I love the boat, but I have a nagging problem. The engine is a stock 302 an this is what I have done to it. This spring I installed a new 600cfm edelbrock carb on it,set the fuel mixture and is running perfect.I also installed a pointless system with a new electronic coil.The ballest resistor is taken out of the system for it all to work correctly.All new plugs,wires,cap,and rotor have been replaced. When the engine is cold it starts perfect,warms up to proper temp and runs perfect.When I shut the engine off I can start it right back up.My problem is when I let it sit for 5 to 10 minutes It takes for ever to start back up.Like 8 to 10 cranks.As the day goes on it gets harder to start.I'll have to crank the engine 3 times,each time 8 to 10 revolutions before it starts and on the third time I have to bury the throttle to get her to start.I have checked everything an i am stumped.At first I thought I was boiling the gas out of the fuel bowls of the carb because of heat.Thats not the case,I can pull the thottle back and I have gas.I check the anti-siphon devise at the tank and it is working.The engine is perfectly time at 10 degrees btc and I have good vacuum on the engine, it 18 inches.The plugs are burning clean. So I have gas and fire but its just hard starting when the engine is warm.When it does start it runs incredible.Need some help guys,PLEASE!