Final answer:
When the main air bleed of a float-type carburetor is clogged, the engine will run too rich due to a higher fuel-to-air ratio resulting from less air being mixed with the fuel.
Step-by-step explanation:
If the main air bleed of a float-type carburetor becomes clogged, the engine will run too rich. This happens because the main air bleed is responsible for mixing air with the fuel in order to create a combustible mixture. When it becomes clogged, less air is mixed with the fuel, causing a higher fuel-to-air ratio. This results in a mixture that is too rich, meaning it has too much fuel and not enough air. This can lead to various engine performance issues, such as rough idling, black smoke from the exhaust, and poor fuel economy.