Mixture forming assembly for closed loop air-fuel metering system

Abstract From the Canadian patent

The idle and main fuel passages of a carburetor are controlled by metering apparatus which is regulated to maintain the idle and part throttle air-fuel mixtures at a selected air-fuel ratio, but during low temperature engine operating conditions the part throttle mixture is leaner than the idle mixture in any particular regulated mode of the metering apparatus. This invention provides a mixture forming assembly which further includes means for leaning the idle mixture only during such low temperature operating conditions; the metering apparatus is then regulated to a rich mode at idle during low temperature engine operating conditions to provide an idle mixture which is leaned to the …