Holley MCarbHoll2110 1957 Carburetor manual
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First set one of the two idle adjusting
needles for the highest steady manifold vacuum
reading. If a vacuum gage is not available get the
smoothest running maximum idle speed by turning
the idle adjusting needle in until the rpm begins to
drop off, then backing the needle off over the "high
spot" until the rpm again drops off. Set the idle
adjusting needle halfway between these two points
for a satisfactory idle mixture setting. Then re
peat the procedure with the other needle.
fine adjustment may vary slightly from this set
ting but should not exceed 1/2 turn difference
between the screws. Should these adjustments
show an increase in idle rpm, reset the throttle
stop screw to obtain the specified idle rpm and
adjust the idle adjusting needles again.
The dashpot, on carburetors for engines
equipped with automatic transmission, is to be
adjusted after the idle speed and mixture settings
have been completed. Close the throttle lever
slowly to the idle position, with the choke fully
open. Set the dashpot adjusting screw to conform
to the clearance specified in the Holley Carburetor
Company Parts Catalog.
1. The automatic choke is accurately
set at the factory to give the best possible all
weather operation. To return the choke to the
original setting, line up the index mark on the
rim of the thermostat cover with the specified
indicator on the choke housing.
If for some reason a richer or leaner
mixture during the warm-up period is desired, it
can be obtained by rotating the thermostat cover.
Never set the index mark on the cover more than
two graduations off the large center indicator on
the housing.
1. Connect a tachometer to the engine.
Start the engine and allow it to warm up thoroughly
Race the engine for a brief interval at wide open
throttle and note the engine speed registered by
the tachometer. If an adjustment is required,
stop the engine and remove the adjusting hole plug
from the governor valve housing. With the ignition
switch off, crank the engine, either by hand or
with the starter, until the governor valve adjusting
screw at the end of the governor valve body ap
pears at the opening. Insert a screwdriver though
the hole and turn the adjusting screw clockwise to
increase speed or counterclockwise to decrease
speed. One full turn of the adjusting screw will
result in a change in top speed of about 150 rpm.
Repeat the adjustment procedure until the speed
is set to specifications. Install the adjusting hole
plug and tighten securely. Attach new locking
wire and seal to the adjusting hole plug and the
adjacent fin.
Figure 40. Carburetor Adjustments
Figure 41 . Carburetor Adjustments
Carburetor service should be performed only
with the use of proper equipment. Approved equip
ment includes float setting gages, together with
other special carburetor tools. In addition, ap
proved specification sheets must be utilized. Refer
to the Holley Carburetor Catalog sheet for the
carburetor being overhauled to find the proper
engine and carburetor specifications.
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