What does a choke do

It controls the flow of fuel and air to the engine to provide an adjustable mixture when starting a cold car. Modern cars have some form of automatic choke while pre-1960 vehicles may have driver controls.

A choke regulates the fuel-air mixture being fed into the engine. This is primarily needed at a cold start but other times demand it as well. Most modern cars have an automatic choke that works independent of driver input. Older cars had several configurations of this going back to the early years of motoring. Look at your lawn mower. It probably has a "Choke" or "Start" throttle position you use when starting it.

The choke creates a richer gas/air mixture to allow the car to start in cold weather.

This is accomplished by the flap on top of the carburetor closing so only a small amount of air can get into the engine when it's cold. Hope that helps! Jim