Quantity and Quality of carburetor mixture.

[Fernando Mendes]

When the idle adjusting screw is near the trouttle plate the adjusting is QUANTITY.When the idle adjusting screw is far away the trouttle plate the adjusting is QUALITY. 

[greg g]

The screw on the carburetor body controls the amount of air admitted to the idle circuit.  The screw on the linkage controls how far the throttle plate remains open at idle, and controls the idle speed.

[Fernando Mendes]

The screw on the carburetor body controls the amount of air admitted to the idle circuit.  The screw on the linkage controls how far the throttle plate remains open at idle, and controls the idle speed.

On the body controls the AIR(ZENITH GMC 1944 pic)

On the bottom controls the GASOLINE.(DFV my Dodge 1952 pic).

On the linkage?

[greg g]

Didn't notice that they were pics of different carbs.  On the first one that screw appears to go into a air passage that routes air from the top of the carb through a cast in passage to the bottom of the carb.  I maintain that that is and air screw that controls the amount of air introduced to the idle circuit.  Most of these simple carbs have a non adjustable idle fuel jet, and the quality of idle is adjusted by controlling the amount of air that passes by the jet, therefor controlling the amount of fuel that can be pulled through the jet.  The screw on the throttle plat linkage adjusts the idle speed.  On the bottom carb it is the same adjustment just in a different location.  Both screws only affect the amount of air passing by the idle circuit jet.neither adjust fuel.

[Fernando Mendes]

16% of air

1% of gasoline.

[Fernando Mendes]

Correcting:15 Kg of air and 1 Kg of gasoline.(ideal mixture for a warmed up engine)

If we have for example:12 or 13 Kg of air and 1 Kg of gasoline it is a RICH mixture(cold engine).If we have 17/1 it is a POOR mixture.9/1 when climbing a aclive.

Air is compounded of 78% of nitrogen,21% of oxygen and other vapor.