1. VENTING VALVES. (Pre-1972)

Function

Bowl venting gives a reliable hot start.

Ventilation is achieved through the venting valve controlled by the carburetor linkage. When driving, bowl ventilation is in the air cleaner. At idle and when engine is stopped, ventilation is outside the air cleaner. This eliminates starting difficulties caused by fuel vapors entering intake manifold when engine is hot.

The venting valves were eliminated on 1972 models in order to conform to federal requirements. Only internal venting is provided on these models.

Problems

1. High fuel consumption can occur if the valve is stuck in the open position.

2. Hot starting problems can occur if the valve is stuck closed.

Adjustment

1. Remove carburetor connecting linkage. (See Fig. 1)

2. Remove vacuum throttle control. (See Fig. 2)

3. Open chokes. (See Fig 3)

4. On late carburetors the vent valve has a stop screw. This has been set at the factory and should not be changed. If it has been tampered with, readjust it to provide 2.5-2.8 mm. vent pin lift. (If changed other carburetor adjustments are affected.) (See Fig 4)

5. On early carburetors, without stop screw, this adjustment must be performed last. This adjustment is made by bending the arm at the notch to provide 2.5‹ 3.0 mm. vent pin lift. (See Fig. 5)