FUNCTION
The vacuum throttle control or vacuum dashpot prevents stalling when the throttle is suddenly closed. It insures a gradual or slow closing which permits the continuing air supply to lean out the rich mixture of fuel that occurs on sudden throttle closing.
It works with emission control but holding the throttle plate open slightly during coasting.
It acts as an idle speed stabilizer when the engine is under load at idle. The pluger extends as the vacuum falls due to the load. This causes the throttles to be opened slightly.
TROUBLESHOOTING
If the dashpot or vacuum control is incorrectly adjusted the driver will experience:
- Braking problems, if the throttle is held open too long
- Stalling
ADJUSTMENTS
VACUUM THROTTLE CONTROL
- With engine idling, remove vacuum hose from throttle control
- set adjusting screw to provide an engine speed of 1100 to 1200 RPM. CAUTION: late units have jam nut on screw which must be loosed first
- Reconnect vacuum hose
- Adjust compression spring with adjusting plate, so that play between actuating lever and adjustment screw is sufficient to slide a piece of paper through (0.1mm). While adjusting nut, do not allow screw to turn
VACUUM DASHPOT
Early models only
- With engien off, hold actuating lever to the point where it just contacts the venting valve
- Adjust dashpot plunger so that there is 2-3mm clearance between the carburetor lever and dashpot plunger
