Carburetor Deceleration Control

Deceleration control assembly consists of an electromagnetic valve, a diaphragm valve and a deceleration mixture screw. Electromagnetic valve is controlled by an RPM switch which receives its impulses from ignition coil. Above 1800 RPM valve is open, below 1800 RPM valve is closed. Diaphragm is operated by intake manifold vacuum. Vacuum can only operate diaphragm when electromagnetic valve is open due to engine speed being above 1800 RPM. Therefore, at engine speeds above 1800 RPM and with increased vacuum, caused by engine overrun during deceleration, an additional mixture is supplied. Require amount of mixture is adjusted by means of deceleration mixture screw.