FM684892 Force DECAL, BOTTOM FRONT

Carburetor Adjustment
(Impco)
There are two adjustments to be made to the carburetor; power mixture adjustment and idle air mixture adjustment.1. Starting Gas Adjustment: With the engine stopped, turn idle adjustment screw (1) all the way in, then back out four full turns. Set the power mixture adjustment butterfly (2) halfway between "R" (rich) and "L" (lean). No further adjustment should be made to the idle adjustment screw or the power mixture adjustment butterfly. Adjust the other carburetor in a similar manner.2. Idle Adjustment: a. After the engine is warm, set the low idle throttle-stop adjustment screw (3) on the carburetor for the best idle speed. (Recommended idle speed 425 RPM.) 750 RPM for engines equipped with electric set generators.) Adjust the other carburetor in a similar manner.
CARBURETOR ADJUSTMENTS
1-Idle adjustment screw. 2-Power mixture adjustment screw.
LOW IDLE ADJUSTMENT
3-Low idle throttle-stop-adjustment screw.(Ensign)
There are three adjustments to be made to the carburetor; starting gas adjustment, idle speed adjustment and main gas adjustment. Two means of making the main gas adjustment are given; with the engine loaded or with the engine not loaded. All three of the adjustments are made with the engine running.1. Starting Gas Adjustments: a. With the engine running and the governor control lever in half speed position and the choke closed, adjust the starting gas adjustment screw (2) on the carburetor. First, adjust for maximum engine speed and then turn the screw (2) out (richer mixture) until the engine speed drops slightly. Tighten the locknut.b. Push the choke control all the way in. The choke is open in this position.2. Idle Adjustment: a. After the engine is warm set the low idle throttle-stop adjustment screw (4) on the carburetor for the best idle speed. (Recommended idle speed 425 RPM. 750 RPM, for engines equipped with electric set generators.)
CARBURETOR AND REGULATOR ADJUSTMENTS
1-Idle fuel adjustment screw. 2-Starting gas adjustment screw. 3-Main gas adjustment screw. 4-Low idle throttle-stop adjustment screw. 5-Economizer connection line (not on turbocharged engines). 6-High idle throttle-stop adjustment screw. 7-Throttle valve control rod.b. Adjust the idle fuel adjustment screw (1) on the regulator for the highest idle speed, then readjust throttle-stop screw.c. Adjust the other carburetor in a similar manner. When the engine is equipped with a Woodward Governor, no low idle speed stop screw adjustment is necessary. Set low idle throttle stop screw (4) so that it hits the low idle stop just before the throttle is completely closed. Adjust the idle fuel adjustment screw for stable engine operation at high idle engine speed.3. Main Gas Adjustment: This adjustment can be made in one of two methods; A-with the engine loaded. B-with the engine unloaded. A. Main gas adjustment with engine loaded: a. In order to set the main gas adjustment screw, each carburetor must be set independently of the other. Disconnect the linkage to the throttle of the carburetor not undergoing adjustments and make sure the throttle is securely held against the low idle stop. If a Woodward governor is used, move the synchronizer control to the high speed position. Hold the throttle valve control rod (7) to keep it from turning and disconnect the linkage from the governor to this rod to make the following adjustment.b. Open the throttle on the carburetor being adjusted to approximately the one-half full load position, and block or lock the throttle control shaft to keep it from turning and simultaneously load the engine to achieve a constant engine speed between 900 and 1200 RPM. Hold the load constant while making the adjustment and make sure there is no governor action. (The governor must not be able to change engine speed while making the adjustment.) Turn the main gas adjustment screw (3) in either direction until maximum speed is obtained, then turn screw (3) in (leaner mixture) until the engine speed drops 10 to 20 RPM. Tighten the locknut. Adjust the main gas adjustment screw on the other carburetor in a similar manner.c. Release the throttle valve control rod (7); it should now be free to turn. (Connect any linkage that has been disconnected.)B. Main gas adjustment with engine unloaded: a. Move the governor control to low idle position and carefully set the idle adjustment as it affects the mixture under no load conditions. Adjust the other carburetor in a similar manner.b. Disconnect the linkage to the throttle of the carburetor not undergoing adjustments, and make sure the throttle is securely held against the low idle stop. On naturally aspirated engines, disconnect intake manifold economizer connection line (5) and plug the inlet manifold connection.c. Turn the main gas adjustment screw (3) in either direction until maximum speed is obtained, then turn screw (3) in (leaner mixture) until the engine speed drops 10 to 20 RPM. Tighten the locknut.d. If economizer connection line (5) was disconnected, unplug the inlet manifold connection and install the line. Adjust the other carburetor in a similar manner.Checking Throttle Valve Synchronization
(Engine Running)
(Impco)
When the engine