1957 requires a pressurized tank if it has not been converted to a fuel pump. It does not have a fuel pump originally and relys on pressure build-up in the tank to push fuel into the carb. A pressure tank has 2 lines - one for fuel to the motor and an air line coming from the motor.
Probably cost you more to add a fuel pump than to buy a pressure tank. I don't think there is a practical way to pressurize a single line vented tank, and again it would be cost-prohibitive.
It must depend on where you are. Somebody will be along soon to tell you how there are dozens of them around for $10. Yeah, right. Especially when the connector costs over $100, new.
