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invert the carburetor and tighten the two screws.
Tighten the screws alternately, a little at a time,
to compress the gasket evenly and eliminate the
possibility of an air leak.
Insert the two throttle body screws and
lockwashers into the throttle body. Settle the new
throttle body to main body gasket in place over
the throttle body screws and check to insure the
proper alignment of the holes in the gasket with
the corresponding holes in the throttle body. Set
the main body in position on the throttle
body ,
Insert the upper end of the pump link in
the pump operating lever and secure it in place
with the new pump link cotter pin.
This completes the reassembly of the Carbu-
retor Model 1904. It is now ready for installation
on the engine.
Check the carburetor mating surface on the intake
manifold for signs of rust or dirt. If it is clean, fit a new
carburetor flange gasket on the manifold and install the
carburetor. Turn the two carburetor mounting nuts down
hand tight and connect and tighten the fuel line and the
distributor vacuum line. Then draw the mounting nuts
down evenly, tightening them alternately a little at a time
until the flange gasket has been compressed and the nuts
are tight. This method of tightening the mounting nuts
will eliminate the possibility of an air leak past the flange
gasket. Cohnect the throttle and choke linkage, checking
the choke plate in the carburetor venturi to insure it opens
fully when the choke control knob is pushed in. Clean
and install the air cleaner.
The moving parts of the dashpot
assembly are not to be lubricated. Any
attempt to lubricate the diaphragm rod
will eventually result in the formation of
sludge in the dashpot, preventing the
proper functioning of the unit.
(1) All carburetor adjustments to be accurate must
be made with the vehicle standing on a level surface.
Start and warm up the engine. When the engine has
reached its normal operating temperature, after first
checking to insure that the choke plate is fully open,
adjust the throttle stop screw to idle the engine at the
rpm specified in the current Holley Carburetor Company
Specifications Catalogue.
Set the idle adjusting needle to give the
highest steady manifold vacuum or, if a vacuum
gauge is not available, the smoothest maximum
idle speed. Clockwise rotation of the idle adjusting
needle will give a leaner mixture, counterclockwise
rotation a richer mixture. An effective setting may be
obtained by turning the idle adjust
needle in until a
drop in engine speed results and then backing the
needle off over the "high-spot" until the engine again
slows down. Setting the idle adjusting needle between
these two points result in a satisfactory idle mixture
setting. Should this adjustment result in an excessive
increase in the idle rpm, reset the throttle stop screw
to obtain the specified rpm and again adjust the idle
mixture setting.
The accelerating pump stroke can be adjusted
to compensate for seasonal or climatic
changes by changing the position of the link
in the throttle lever. The hole in the lever
nearest the throttle shaft is the normal setting
and should be satisfactory for nearly all
operating conditions. Should a richer
accelerating pump discharge be required for
extreme cold weather operation, the pump
link is to be placed in the outer hole in the
throttle lever.
The dashpot on carburetors for engines
equipped with automatic transmissions is to be
adjusted after the idle speed and mixture settings have
been completed. Close the throttle lever to the idle
position. Set the dashpot adjusting screw so the
clearance specified in the current Holley Carburetor
Company Specifications Catalog is obtained between
the dashpot adjusting screw and the diaphragm rod
with the rod in the fully compressed position. To
assure an accurate adjustment, check the choke plate
to insure it remains fully opened while setting the
dashpot adjusting screw.
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