PART 2 2
Maintenance Operations
Fig. 22-Accelerating Pump, Idle Fuel Mixture and Idle (Hot Engine)
Speed Adjustments-Holley Carburetors
The final engine idle speed may be
varied to suit the conditions under whim
tbe car is to be operated.
6. Shut off the engine. Check the
fast (cold engine) idle speed.
Fast (Cold Engine) Idle
Speed Adlustment
On a Ford 4-V (4300) carburetor the
fast (cold engine) idle adjustment
screw location is shown in Fig. 21.
I. Loosen the choke cover so it can
rotate. Be sure the thermostatic spring
elM! Is engaged in tbe choke lever slot.
2. Rotate the choke cover to a 90-
degree rich position.
3. Position the fast idle speed adjust-
ing screw end to the kickdown step on
the fast idle cam and hold in this
position.
4. Check the fast idle cam clearance
between the lower edge of the choke
plate and the air horn wall.
S. Adjust the fast idle cam clearance
to specifications by turning the adjusting screw clockwise to increase the
clearance or counterclockwise to decrease the clearance.
6. Install the thermostatic choke
cover to the specified index setting and
tighten the cover retaining screws.
7. Place the transmission selector
lever in neutral and turn off the en-
gine. Switch off the headlarnps and the
air conditioner (if so equipped). Re-
move the tachometer.
On cars equipped with a vacuum
release parking brake, connect the
vacuum line to the vacuum power unit
of the automatic vacuum release parking brake assembly.
8. If the car is equipped with an
automatic transmission, check the antistall dashpot for proper adjustment.
speed adjusting screw (Fig. 22) equally
and alternately. Turn the screws inward to increase the speed and outward
to decrease the speed. Be sure the fast
idle screw is not toudling the fast idle
cam when performing this adj~tment.
2. Adjust the idle fuel mixture by
turning each idle miJcture screw inward (Figs. 22, 23, or 24) evenly and
alternately, starting with the front
carburetor and finishing with the rear
carburetor, until the engine rpm begins
to drop (due to the lean mixture). Turn
each screw outward until t~ engine
rpm begins to drop (due to the rich
mixture); t~n turn each screw inward
for maximum engine rpm and smoothness. Always favor. slightly rid! idle
fuel mixture. Final adjustment of the
idle fuel mixture screws should be
within lis turn of each other.
3. After the correct engine idle mixture has been obtained, dleck the idle
speed with the transmission selector
lever in neutral and manually opening
and cl~ing the throttle. Adjust the
idle speed to specification, if required.
If the car is equipped with an auto-
matic transmission, position the selec-
tor lever in drive range to check and
adjust the idle speed to specification
if necessary.
The final engine idle speed may be
varied to suit the cooditions UIMler
which the car is to be operated.
4. Shut off the engine. Check the fast
(cold engine) idle speed.
HOLLEY ~V CARBURETOR
Refer to Preliminary PrelNlrBtion-
All Vehicles, above.
Adjust Accelerating Pump
Lever
To satisfy acceleration requirements
in various climates, the accelerating
pump discharge can be adjusted. The
bottom hole (No.2) in the cam pro-
vides a maximum pump discharge for
extreme cold weather and the top hole
(No.1) provides the minimum pump
discharge for warm weather operation
(Fig. 22).
For summer operation, install the
adjustment screw in hole No. I. For
winter operation, install the adjust-
ment screw in hole No.2.
On cars equipped with Dual Holley
~ V carburetors, the screw should be
int~same hole for each carburetor unit.
Initial Idle Speed and Fuel
Mixture Adlustments
The idle fuel mixture is controlled
by the idle fuel mixture adjusting
screws (needles) located in the primary metering blocks of the carburetors (Figs. 22, 23 or 24). The idle (hot
engine) speed adjusting screw location
for each carburetor is shown in Fig. 22.
1. Initially set the idle mixture by
turning the idle mixture screws inward
until they are lightly seated; then turn
the screws outward the specified turns.
Do not turn the needles tightly against
the seat as this may groove the ends. If
a needle is damaged, it mmt be replaced
before a satisfactory fuel mixture can
be obtained.
2. Turn the idle (hot engine) speed
screw outward on each carburetor
until the throttle plates close tight in
the throttle bores. It may be necessary
to back the front carburetor fast (cold
engine) idle adjusting screw (Fig. 24) to
close the plates tight in the bores. Set
the idle speed adjustment screws to
just make contact with the stops on
the carburetor bodies and turn them
inward the specified turns.
Refer to Group 10 of the appro-
priate Shop Manual for specifications.
Final Idle (Hot Engine)
Speed and Mixture
Adjustments
1. Adjust the engine idle speed to
specifications by turning each idle