I was adjusting the float level and noticed that what you are actually doing is getting the gasoline up to the tip of the main jet (the jet you see if the carb is not mounted on the car). If you look at pictures of the proper float level, you will see that the gas level in the carb corresponds to location of the tip of the main jet. If the carb leaks, the gas is coming over the top of the main jet and into the carb intake and out on to the ground. You also have to remember that if the carb doesn't leak on level ground, it may leak if the car is parked on a hill going up! Before you mount the carb, fill the carb with gas and then looking down into the throat, tip the inlet upwards and you sill see the gas rising in the tip of the main jet. I hope I haven't been too confusing but I have been adjusting the float level first by the dimension, and then checking that the gas level gets very close to the jet outlet but no so close that it leaks. I find the car runs that much better if the gas is sitting just below the tip and is easily picked up by the air flow through the carb. Happy motoring, Ed