YF Metering Rod Adjustment
The adjustment below is for early Carter YF carburetors that don’t have an adjusting screw at the top of the metering rod. Most YFA carburetors would have the star type of adjusting screw.
This adjustment is important and should be performed anytime the carburetor is rebuilt, or the metering rod replaced. With the throttle valve seated (this means the idle screw is not holding the valve open) in the bore of carburetor, press down on upper end of diaphragm shaft (C) until diaphragm bottoms in vacuum chamber. On carburetors which have the projection (D) on the pump lifter link, metering rod should contact the bottom of the metering rod well (E), and metering rod arm (F) should contact lifter link (G) between springs and at supporting lug (D). Adjust by bending lip (H) up or down. In the illustration there is a tool that can be used to hold down the diaphragm, but chances are you won’t have one of those and it isn’t that big of a deal to hold it down.
On models that do not have the projection (D) on pump lifter link, the metering rod should bottom in the metering rod well (E) and flat of metering rod arm (F) should make parallel contact with flat of pump lifter link (G). Adjust by bending the lip (H) up or down.