https://youtu.be/xa_pCSQaS-c

PUMP ADJUSTMENT TYPE A

BOWL VENT VALVE

The fuel bowl is vented through an external vent connected by a hose to fuel evaporation carbon canister.

Fully depress vent valve into valve bore. Measure clearance between flat portion on vent rod and fully seated valve.

If adjustment is required, bend vent rod at point where it contacts accelerator pump lever.

Another Type of 2100 Vent

With the throttle closed the rod circled in green is bent so that the venti slightly open. When the throttle is opened the vent will close.

DASHPOT

Make sure dashpot is not holding the throttle open when adjusting slow idle.

FAST IDLE ADJUSTMENT

The fast idle adjusting screw contacts one edge of the fast idle cam. The cam permits a faster engine idle speed for smoother running when the engine is cold, during choke operation. As the choke plate is moved through its range of travel from closed to open, the fast idle cam pick-up lever rotates the fast idle cam. Each position on the fast idle cam permits a slower idle rpm as engine temperature rises and choking action is reduced.

Make sure the curb idle speed and mixture settings are adjusted before attempting to set the fast idle.

The following adjusting procedure is suggested:

1. With the engine at normal operating temperature, air cleaner removed and tachometer attached, manually rotate the fast idle cam until the fast idle adjusting screw rests on the second (kickdown) step of the fast idle cam.
2. Turn the fast idle adjusting screw inward or outward, as required to obtain the specified fast idle rpm.

CHOKE PULLDOWN ADJUSTMENT

The vacuum-operated choke modulator is used in place of the vacuum piston. It tailors initial choke opening after engine start, to the existing tempera­ture requirement.

The following adjusting procedure is suggested:

1. With engine at normal operating temperature, loosen thermostatic spring housing retainer screws and set the housing 90° in the rich direction.
2. Disconnect and remove the choke heat tube from the choke housing.
3. Turn the fast idle adjusting screw outward one full turn.
4. Start engine and check for the specified clearance between the lower edge of the choke plate and the air horn wall.
5. If the clearance is not within specifications, tum the diaphragm stop screw (located on the underside of the choke diaphragm housing):Clockwise to decrease clearance.Counterclockwise to increase clearance.
6. Connect choke heat tube.
7. Set choke thermostatic spring housing to specifica­tion.
8. Adjust fast idle speed to specification.

IDLE SPEED AND MIXTURE ADJUSTMENTS

LIMITERS AND LIMITER STOPS

All carburetors manufactured for use in the US since 1968, are equipped with idle fuel mixture adjusting limiters. The limiters control the maximum idle richness and help prevent unauthorized persons from making overly rich idle adjustments.

The plastic idle limiter cap is installed on the head of the idle fuel mixture adjusting screw(s). Under no circumstances are the limiters or limiter stops to be removed or mutilated to render the limiters inoperative. On the Autolite 2100, the power valve cover must be installed with the limiter stops on the cover in position to provide a positive stop for tabs on the idle adjusting limiters.

These days, we cut them off and do what we want.

ACCELERATOR PUMP STROKE ADJUSTMENT

The accelerating pump stroke has been set to help keep the exhaust emission level of the engine within specified limites. The additional holes provided for pump stroke adjustments are for adjusting the stroke to accomodate specific engine applications. The stroke should not be changed from the specified setting.

The primary throttle shaft lever (overtravel lever) has four holes and the accelerating pump link has two holes to control the accelerating pump stroke. The pump operating rod should be in the specified hole in the overtravel lever and in the inboard hole (hole closest to the pump diaphragm) in the accelerating pump link.

The following procedure is suggested:

1. Press the tab end of the retaining clip toward the rod to release the rod from the clip.
2. Position the clip over the specified hole in the over-travel lever.
3. Press the ends of the clip together and insert the operating rod through the clip and overtravel lever.
   1. Release the clip to engage the rod.

FAST IDLE CAM CLEARANCE ADJUSTMENT