This manual introduces the OS TYPE 7D carburetor's user manual
This manual provides instructions for the O.S. Engines Type 7D carburettor, which features an automatic mixture control device. It details the function of three adjustable controls: the Needle-Valve, Mixture Control Screw, and Throttle Stop Screw. The document explains how to set provisional values and adjust the carburettor for steady idling and smooth acceleration.
The controls are the Needle-Valve for adjusting mixture strength at full throttle, the Mixture Control Screw for part-throttle and idling, and the Throttle Stop Screw for setting the closed rotor position.
It is recommended to open the Needle-Valve 7 1/2 to 2 turns from the fully closed position before starting the engine.
Adjustments should be made progressively by turning the screw 15 to 30 degrees at a time, ensuring the engine is stopped before making changes.