Demon Fuel Systems 1563010VE - Manual (Page 12)

12
Metering Blocks
The metering block is the part of the carburetor having the two-fold job of controlling the flow of fuel
into the venturi along with the duty of mixing air and fuel prior to its introduction to the main air
stream. This is done through a series of sized orifices located in the metering block. These orifices
will be discussed from a tuning standpoint.
The metering blocks from Demon Carburetion
™ are made of billet aluminum. Each block is
specifically tuned for its specific application. As mentioned before, this tuning is accomplished through
the various sized orifices in the block. Understanding the function of these various devices is critical
to understanding how the carburetor works.
Idle Feed Restrictor
The idle feed restrictor controls the amount of fuel that enters the idle circuit from the main well. This
orifice controls the amount of fuel available for the idle circuit. If all other tuning results in a lean or
rich idle circuit, an adjustment here may be necessary. As with any fuel restrictor, the larger the hole
in the restrictor, the more fuel that will be introduced into the idle circuit. Make small changes, .001" or
.002", to all four restrictors and work towards your desired tuning point.
CAUTION: The idle feed restrictors are drilled from the factory. If they are drilled larger, you cannot
go back. Modification is not recommended.
Figure 16 Figure 17
Emulsion Bleeds
There are six (6) emulsion bleeds per metering block, three (3) for each main well. These orifices play
a part to control the density of the fuel in the block by metering the amount of air that is introduced
into the fuel in the main well. This, in conjunction with the air bleeds in the main body, help to control
the shape of the fuel curve. The emulsion circuitry of your Speed Demon
™ has been engineered
through extensive wet flow, dyno and street & track testing. A note of caution: tuning of emulsion
bleeds should be done only by those with a deep knowledge of carburetors, otherwise, a poor running
engine or damaged internal engine parts could be the result.