Vacuum Control Valve Adjustment

With engine at normal operating temperature and using a stop watch or watch with sweep second hand, raise engine speed to 3000 RPM (without load) and then immediately release throttle. It should take 3-5 seconds for engine speed to lower from 3000 RPM to 800 RPM. If time required is less than three seconds, turn adjustment screw on control valve clockwise. If time is more than five seconds, turn adjustments screw counterclockwise.

Fig 1: Subaru FF-1 1300G Timing Marks

Courtesy of SUBARU OF AMERICA, INC.