The air fuel ratio of the petrol engine is controlled by Carburetor
The ratio is about 15:1 fuel to air.
Ideally it is 14.7 air to 1 fuel in an internal combustion engine.
It is when the "correct" air to fuel ratio is used to completely burn the fuel in question in an internal combustion engine. If exactly the correct amount of air is used this is called the stoichiometric mix.
A 14.7 to 1 air/fuel ratio.
Ensures that all the fuel mixes with the air creating a proper air to fuel ratio to produce combustion.
Regulates the amount of fuel to the engine to maintain the fuel/air ratio at the proper mixture
to supply the engine a mix of air and fuel at 14.7 to 1 ratio.
make the fuel sufficient burning
To adjust the air-fuel ratio on a Holley 4160 carburetor, first, ensure the engine is at operating temperature. Then, use a vacuum gauge or an air-fuel ratio meter to monitor performance. Adjust the idle mixture screws, located on the sides of the carburetor, by turning them clockwise to lean the mixture and counterclockwise to enrich it, aiming for the highest vacuum reading or optimal air-fuel ratio. For more precise tuning, consider adjusting the main jets if needed, but this typically requires removing the carburetor.
14.7:1
There is no required a/f ratio on a diesel. It can be as low as 100:1 at no load idle.