HDABOB's Tech Notes:
Do you ever wonder how the carburetor works?
Let me explain it to you...
The components of the carburetor consist of:
The carburetor is a device that vaporizes gasoline and mixes it with air in the proper ratio for combustion in an internal combustion engine. Normally the ratio of fuel to air is about 1:15 by volume. That is one part fuel to fifteen parts air. A higher ratio is called a rich mixture and a lower ratio is called a leaner mixture.
The carburetor has a FLOAT CHAMBER that is supplied with fuel from the FUEL TANK. The fuel is forced through a FUEL FILTER under pressure from the FUEL PUMP. The float chamber contains a FLOAT VALVE that regulates the flow of fuel into the chamber. When the float chamber is full of fuel, the float valve stops the flow of fuel until needed again.
The JET NOZZLE is situated within an air chamber that is narrow at one point. The narrowing in the chamber is called a VENTURI.
When the engine is running, the motion of the pistons creates a vacuum, drawing air into the air chamber, where it is accelerated by the venturi. This high velocity air creates a low pressure region that the jet nozzle (which extends into the air chamber) draws a fine spray of fuel drawn from the float chamber into the venturi. Here it mixes with the air. The mixture of fuel and air is then fed into the cylinders where it is ignited.
The THROTTLE VALVE, which is activated by the ACCELERATOR PEDAL, regulates engine speed by regulating the amount of fuel/air mixture that enters the engine.
The CHOKE is at the entrance to the carburetor and restricts the amount of air entering the carburetor, thereby creating a richer mixture for the spark plugs for starting the engine when cold. The choke valve gradually opens as the engine warms up, reducing the richness of the mixture. Carburetors use various means to ensure an optimum mixture for differing conditions, including idling and rapid acceleration, as well as varied altitudes.
Whenever you have a problem such as a vacuum leak, the engine will die when cold and run badly when warm. The carburetor must be sealed from outside air leaks for it to work properly.
Additives added to the fuel system are not necessary. The use of high quality gasoline is beneficial because they contain detergents that clean the fuel system as you drive.
...and that's the way the carburetor works!!
Back to Top
Next: Ignition system
Index of Symptoms
HDABOB's Mobile Service 09/15/2007