Throttle Positioner (Except 1973)

When engine speed of over 1600 RPM is detected by governor switch, it supplies current to solenoid of throttle positioner. This opens a valve and allows intake manifold vacuum to diaphragm of throttle positioner. This causes throttle valve to be held at 1350-1450 PM (1400-1450 RPM for 1972) at no load. When engine RPM decreases below 1600 RPM governor switch closes solenoid valve cutting off vacuum. A leak jet in throttle positioner allows throttle valve to gradually close as pressure inside chamber approaches atmospheric pressure.