Owners manual

9
3. Now that the idle mixture is set, it may be necessary to go back and reset the idle speed using the curb idle speed screw,
as shown in Figure 9.
4. If a vacuum gauge is not available, use a tachometer to obtain the highest RPM.
Figure 10 Figure 11
ROUGH IDLE AND VACUUM LEAKS: If a rough idle persists after the engine has been started and the mixture screws
adjusted, check for manifold vacuum leaks. These could result from unplugged vacuum fittings or a carburetor flange gasket
that was torn during installation. Recheck for proper attachment of all vacuum lines and check the lines for cracks.
If the manifold was changed, a manifold vacuum leak could occur at the cylinder head/manifold surface due to damaged gaskets
or improper torquing. Frequently, manifold vacuum leaks occur from the valley side of the manifold. These are very difficult to
detect, unless a discernible whistle can be heard.
NOTE: In most cases, when rough idle occurs after a carburetor/manifold change, they result from manifold vacuum leaks
similar to those described above. Assuring a proper manifold installation rather than assuming the carburetor is not
functioning properly will ultimately save time.
FLOAT LEVEL ADJUSTMENT:
NOTE: Do not try to remove the sight glasses. It takes special tools to install these and it is not recommended that they be
removed.
Primary and secondary float adjustments are set at the factory, but variations in fuel pressure could cause a change in these
settings. To aid in adjustment of the float levels, clear sight glasses are installed from the factory. The following procedure
shows how to make these adjustments:
1. Start the vehicle.
2. Observe the sight glass for the fuel level. If none is seen, the level is too low. If it is higher than the middle of the sight
window, it is too high. NOTE: A properly set float level will have the fuel level located at the middle or slightly below the
middle of the sight window, as shown by the line in Figure 12.
Figure 12