www.barygrant.com has got a ton of good info on this topic. Basically, their "fuel Can Test" pretty much makes the line size / pump size topic a moot point. It's based on how many seconds it takes to fill a 1 gallon gas can. Example: If you have a 10 second car, you will need enough fuel ( at the carb ) to fill a 1 gallon fuel can in 25 seconds. Smoking is prohibited while running this test