Demon Fuel Systems 5563020GC - Manual (Page 2)

2
INTRODUCTION
Demon Carburetors ™ , the first new design in racing carburetion in 40 years, have many unique
features that make them the ultimate choice for performance enthusiasts, like yourself. This manual
will discuss the special points and unique features of the Demon carburetors, and the correct
procedures for their proper installation and tuning. The goal is to help you understand the thoughts
behind the Demon, and to increase your knowledge of carburetion on a whole. Please read and
understand this manual completely to assure that you get the most out of your new Demon
carburetor.
Figure 1
INSTALLATION
Checking the Baseline Adjustments
All baseline adjustments have been made at the factory during the final assembly stage of each
carburetor. These settings should allow initial start and warm up of the engine. However, in order to
assure safe operation, and to assist with fine tuning that will occur later, please check and make note
of the following adjustments, prior to installing the carburetor on the engine.
Throttle and Accelerator Pump Linkage
1. Check the travel of the throttle linkage to be sure no damage has occurred during handling or
shipping after its final assembly. The carburetor should open smoothly to wide open throttle, and
return to its full closed position when the linkage is released. At wide open throttle, all butterflies
should be parallel to each other, at about a 90º right angle to the baseplate gasket surface. Do not
attempt to run a carburetor that opens the secondaries past full throttle, or sticks or binds at any
point in its travel.
2. When the carburetor is in the closed (curb idle) position, there should be no play in the adjustment
of the accelerator pump arms. The pump levers should begin compressing the pump diaphragms
as soon as the linkage begins to move. Play in the pump arm linkage will delay the fuel discharge,
and the result is usually a stumble or hesitation as the carburetor begins to open. At wide open
throttle, check to be sure that .015" to .020" travel remains in the accelerator pump linkage. If the
pump diaphragms bottom out, premature wear or binding in the linkage will occur.