Demon Fuel Systems 4402020VE - Manual (Page 3)

3
Figure 2
3. Slop in the linkage can be adjusted out by either tightening or loosening the lock nut. This will
control the length of the compressed spring. Slightly bend the cam follower to adjust for linkage
that bottoms out. Remember, it may take a balance of both cam follower and spring adjustments
to get the system working best for the application. Different cam profiles are available which can
alter the timing, volume, and duration of the pump shot. If pump cams are changed, it may be
necessary to re-adjust the linkage.
Closed Butterfly Position
The initial setting of the closed butterfly position will vary slightly between carburetor model sizes and
fuel types. Most gasoline carburetors will have the butterflies adjusted with a small length
(approximately .020", looking like a square) of the idle transfer fuel slot visible below the bottom edge
of the butterflies (Fig. 3).
Figure 3
Primary and secondary butterflies should be open equal amounts, and never seated tightly against
the throttle bores in the baseplate. If idle seems a little rich or if you cannot adjust idle speed low
enough, close the secondary butterflies more than the primaries. Butterfly position is adjusted using
the idle set screws in the baseplate (Fig. 4). Turn the screws clockwise to open the butterflies, or
counterclockwise to close them down. Be sure to note the adjusted position of your model carburetor,
as this can be important information used later during fine tuning.