For a long time, most car engines were using multi-point port injection that sprays fuel directly at the intake valves. Today, engines are increasingly commonly direct injected. A problem of direct injection engines is that the intake valves often suffer from carbon deposits. Apparently the port injected engines used the gasoline as a cleaning fluid to remove carbon deposits from intake valves. As a response to the problem of direct injected engines suffering from intake valve carbon deposits, some manufacturers like Toyota don't have only direct injection but rather dual injection so an engine has both port and direct injection at the same time.
Do traditional carbureted engines have the same property that gasoline cleans the intake valves from carbon deposits? Or is the carburetor so far away from the valves that all liquid gasoline has already evaporated by the time the airstream reaches the intake valves?
