Figure 4-54. Idle Mixture Adjustment

Figure 4-54. Idle Mixture Adjustment

Figure 4-55. Idle Speed Adjustment

damaged it must be replaced before a satisfactory

fuel mixture can be obtained.

c. Turn on the head lamp to place the alternator

under a load condition in this manner in order to

4-54. INITIAL IDLE SPEED ADJUSTMENT (See

obtain the specified idle speed during the

f i g u r e 4-55). A stop screw at the throttle lever

adjustment procedure.

flange of the carburetor controls the engine idle

speed. Turn the screw outward (counterclockwise)

d. Attach a tachometer to the engine.

to increase the engine idle speed and inward

(clockwise) to decrease the engine idle speed.

e . Make sure the choke plate is fully opened.

Initial idle adjustment will automatically set the

W i t h the transmission selector lever in neutral

preliminary fast idle (hot engine) RPM required.

position, turn the idle speed adjustment screw in a

direction to obtain the specified engine idle RPM

a . Position the choke control lever so that the

(500 to 550). Open the throttle by hand and allow

choke plate is fully open.

it to close normally.

b. Seat the throttle plate in the throttle bore. Set

f. Place the transmission selector lever in

the idle adjusting screw to just make contact with

F O R W A R D range and adjust the idle speed to

t h e cam contour; then, turn the screw outward

specifications (500 to 550). The engine idle speed

(counterclockwise) l-1/2 turns.

is adjusted first with the automatic transmission

4-55. FINAL IDLE MIXTURE AND SPEED

selector lever in neutral. The final idle speed and

fuel mixture adjustments are made with the

A D J U S T M E N T . The final idle fuel mixture and

transmission selector lever in gear.

engine idle speed is adjusted to settings for a hot

engine.

g. Turn the idle fuel mixture adjustment screw

inward until the engine RPM begins to drop due to

Operate

the engine until

the engine

the lean mixture. See figure 4-54. Turn the idle

temperatures are stabilized at a hot, normal

fuel mixture screw outward until the engine RPM

operating temperature.

increases and begins to drop; then, turn the idle

mixture screw inward for maximum engine RPM

b. Place the transmission control lever in neutral

and smoothness. Always favor a slightly rich fuel

position and set the parking brake.

mixture.

4-40