i have a l98 that i put in my car used to have a 305 not new but new to me and a 650cc holly street carb that is new on it,this is kind of a wierd question but its very hard to get a nice startup on my car, weird thing is in the morning i press the gas once to the floor and let off and turn the key starts right up, but in the day if i go into the store for more than 20 min then come back out i press the gas once and try and start and i have to sit there for like 5-10 seconds starting it and almost playing with the gas also happens like if the car sits there for an hour or so but it will start right up if i'm getting gas or something like that, and it does the same thing if i don't press the pedel. my old carb before i changed the engine out never did this, i know i need a new distributor maby thats the reason i'm not sure anyone ever had this problem occur

 

try checking your carb. my friend had the same exact problem! it starts up right away when his day starts, then when he went to the store and leaves his car sitting for 15-20 minutes he had to wait about the same time. until he was using carb cleaner to get it a quick start for him so he would not have to wait that long. until he bought a new carb and never had the problem again.