Owners manual
9
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:
Float adjustments are set at the factory, but variations in fuel pressure could cause a change in these settings. The following
procedure shows how to make these adjustments:
WARNING! Extreme caution must be exercised while adjusting the float levels, as fuel spillage may occur.
1. Start the vehicle. Turn on the electric fuel pump (if so equipped)
2. Carefully remove the float level sight plug.
3. Observe the sight plug hole for the fuel level. If none is seen, the level is too low. Fuel should be even with the bottom of
the sight plug hole. If fuel comes pouring out of the sight hole, the float is set too high.
NOTE: A properly set float level will have the fuel level located at the bottom edge of the sight hole, as shown by the line in
Figure 10.
Figure 10
4. To adjust, shut down the engine.
5. Loosen the lock screw on top of the fuel bowl just enough to allow you to turn the adjusting nut. Hold the screw in position
with the screwdriver.
6. Using a 5/8” wrench, turn the adjusting nut in the appropriate direction: Clockwise to lower float level and counterclockwise
to raise the float level.
7. Turn the adjusting nut in increments of 1/4 of a rotation.
8. Retighten the lock screw.
9. Restart the vehicle and observe the sight plug hole.
10. Repeat steps 1 through 8 as necessary.
11. Reinstall sight plug when complete.