| 1. |
Remove the air cleaner, exercising care to carefully detach any
vacuum lines from the air cleaner and marking them so they can be
reassembled to the air cleaner in the same manner.
|
| 2. |
Remove the existing carburetor by the following procedure:
A. Carefully disconnect the fuel line.
WARNING: Carefully protect the open end of the fuel lines, so that no foreign
particles can enter. Wrap the end of the fuel line with a clean lint-free cloth.
B. Disconnect and mark all vacuum lines and wiring (if any) to the carburetor.
C. Disconnect the PCV hose.
D. Disconnect the choke rod or heat tubes (if equipped).
E. Disconnect and remove the throttle linkage and automatic kickdown linkage.
SAVE ALL RETAINING CLIPS.
F. Unbolt and remove the carburetor from the manifold. |
| |
|
| 3. |
If
the intake manifold is being changed at this time, install the new
manifold according to the manifold’s manufacturer’s directions.
Since we are not familiar with all manifold instructions, Holley
cannot accept responsibility for their validity. We recommend that
you only use Holley / Weiand manifolds, which
you can find at your nearest dealer. |
| |
|
INSTALLATION NOTES:
|
| CHRYSLER APPLICATIONS |
| |
WARNING: This carburetor is not designed for use with any Chrysler automatic
overdrive transmission. SEVERE transmission damage may result from improper
application use.
|
| 1. |
Unless you are replacing an existing Holley carburetor (which
already has a lever extension arm), you may need to purchase and
install a throttle lever extension (Holley P/N 20-7) on the
carburetor. Remove the throttle stud and nut from the original
carburetor. You can purchase a new stud from your Holley dealer
(Holley P/N 20-36). Install the stud in the throttle lever
extension (Figure 1). See the appropriate service manual for
transmission adjustment.
|
| |
Figure 1 - Chrysler applications
|
| FORD APPLICATIONS |
| |
WARNING: This carburetor is not designed for use with any Ford automatic
overdrive transmission. SEVERE transmission damage may result from improper
application use.
NOTE: Unless replacing an existing Holley Carburetor, you will need to purchase
Holley P/N 20-91, spring and perch kit, for Ford automatic transmissions.
|
| 1. |
Install the new throttle ball, lockwasher, and retaining nut to the
carburetor throttle lever in the same position as the existing carburetor.
|
| 2. |
Insert the transmission kickdown screw with the black retaining clip on the
transmission kickdown lever (Figure 2). This assembly must be installed
according to the detailed drawing (Figure 3). See the appropriate service manual
and page 8 of these instructions for proper transmission adjustment.
|
| |
Figure 2—Ford applications
|
| 3. |
Remove the lock out screw from the kickdown lever (Figure 4).
|
| 4. |
Install the transmission kickdown spring between the transmission kickdown
lever and spring perch (Figure 2).
|
| |
Figure 3—Ford applications |
Figure 4—Ford applications |
| GM APPLICATIONS |
| |
WARNING: If you are using this carburetor with a GM overdrive transmission
TH700R4 or a TH200R4, you must use a transmission kickdown cable bracket (Holley
P/N 20-95) and stud (Holley P/N 20-40). Otherwise, SEVERE transmission damage
WILL result. This carburetor is not designed to work with ANY other automatic
overdrive transmission.
|
| 1. |
Remove the throttle cable ball and automatic transmission kickdown stud (if
any) from the original carburetor, and mount these in similar locations on the
Holley throttle lever. If the original throttle cable is too large, a new
throttle ball or stud is needed (Holley P/N 20-2 or 20-38). See the appropriate
service manual for transmission adjustment.
|
| INSTALLATION: |
| 1. |
Install the carburetor-mounting studs (not provided) in the proper
location on the intake manifold carburetor flange.
|
| 2. |
Place
the new carburetor flange gasket, provided with the carburetor, in
the proper position on the intake manifold.
|
| 3. |
Place
the carburetor on top of the flange gasket on the manifold.
Install the hold-down nuts and snug down progressively in a
“crisscross” pattern (60-80 in./lbs.), as shown in Figure 5.
|
| |
Figure 5 |
| |
WARNING: Overtightening may result in a warped or cracked carburetor throttle
body.
|
| 4. |
Before connecting the linkage, operate the throttle lever to
ensure the correct travel (no sticking or binding), by opening to
wide-open throttle and back to closed throttle several times.
Correct any sticking or binding conditions before proceeding.
|
| |
WARNING: Any sticking, binding, or other interference in the throttle linkage
could result in uncontrolled engine speed. This could result in engine damage or
personal injury.
|
| 5. |
Reconnect the throttle and transmission kickdown linkage and throttle return
spring (Holley P/N 20-89). Operate the carburetor throttle lever by hand to
ensure the correct travel (no sticking or binding) by opening to wide-open
throttle and back to closed throttle several times. Correct any sticking or
binding conditions before proceeding.
|
| |
NOTE: With the engine turned off, have an assistant slowly press the accelerator
pedal to the floor, while you watch the throttle for any sticking or binding.
Correct any sticking or binding conditions before proceeding. Also, ensure that
you are reaching full throttle. Many performance problems are traced to partial
throttle openings from improperly adjusted linkage. Secondaries will not open
mechanically during this procedure.
|
| |
Figure 6 |
| 6. |
Reconnect the appropriate vacuum hoses to the carburetor, noting
the correct fitting from Figure 6 and 7. Replace any cracked or
dry rotted hoses at this time to prevent any vacuum leaks.
A. The full manifold vacuum source in the front of the throttle body provides
vacuum for proper operation of the air cleaner, the pump diverter valve (if
equipped), AC/Cruise, and/or the temperature sensing valve. If vacuum for more
than one component is needed, use small plastic vacuum “T”s (available at most
automotive stores).
B. The timed spark fitting in the choke side of the primary metering block
provides vacuum for the operation of the distributor vacuum advance. Connect the
hose to the distributor, spark delay valve, and/or temperature sensing valve as
originally connected. Again use “T”s as necessary. If any questions arise about
the hose connections, consult the proper service manual.
|
| 7. |
Connect the PCV hose to the PCV fitting in the carburetor.
|
| 8. |
Connect the power brake hose (if applicable) to the fitting as shown in
Figures 6 or 7. |
| |
Figure 7 |
| |
WARNING: During the fuel line installation, DO NOT allow any foreign particles
to enter the fuel lines, which could then cause flooding and may result in a
fire.
|
| |
NOTE: If installation requires cutting the metal fuel line, cut the fuel line
with a good tube cutter. This will minimize the chance of producing metal chip
particles. If a hacksaw must be used then metal chips must be removed.
WARNING: In all cases where the fuel line has been cut, it is essential that it
be clean to ensure that no metal particles enter the fuel bowl after the new
carburetor installation. Remove the fuel line at the pump and blow the line
clean with compressed air. DO NOT use the procedure where the coil wire is
disconnected, the engine cranked for a few revolutions, and the fuel collected
in a container. This procedure is unsafe because sparking can occur either at
the coil or at the distributor end of the coil wire and ignite any fuel spilled
in the engine compartment.
CAUTION: The use of a quality in-line fuel filter, such as Holley P/N 162-523 is
mandatory as a safeguard against possible flooding, which could result from
unfiltered particles becoming lodged between the fuel inlet needle and its seat.
This can result in fire if a spark is present or backfire occurs in the engine
compartment. Air cleaner filter elements should be blown clean with compressed
air at 6,000 miles and replaced at 12,000 miles to ensure maximum protection.
Now would be the perfect time to upgrade to a Holley Powershot air filter.
|
| 9. |
For
choke hookup, attach the bayonet end of the long electrical lead
supplied to the positive terminal on the choke cap. The other end
must be connected to an ignition-activated 12-volt source. The
distributor side of the ignition coil is NOT a 12-volt source. It
is a 7-9-volt source after cranking. WARNING: Connecting the choke cap to the ignition or ignition coil could result
in unacceptable choke operation, poor fuel economy, and possible engine
misfiring, since the voltage delivered to the spark plugs will be severely
reduced by the drain imposed by the choke cap. Suitable ignition activated
12-volt sources are most electrical relays, as well as the leads to accessories,
such as windshield wipers. DO NOT connect this wire to the original equipment (O.E.)
electric choke source. This may not be a 12V source.
|
| 10. |
Check
the voltage source with a volt-ohm meter to assure proper voltage
and choke operation.
|
| 11. |
Start
the engine and check the fuel line and inlet fitting for possible
leaks.
NOTE: The recommended fuel pressure is 5-7 psi.
|
| 12. |
Recheck to assure all existing vacuum hoses are attached properly.
Plug any fittings not used.
|
| 13. |
With
the engine at operating temperature, set the idle speed to the
manufacturer’s specifications (see page 9 for idle adjustment).
|
| 14. |
Shut
off the engine and readjust the throttle operated transmission
linkage, if necessary. On installations that have a kickdown-actuating switch on the
passenger’s side of the firewall, it might be necessary to readjust it according
to the manufacturer’s service manual.
|
| |
FORD APPLICATIONS WITH AUTOMATIC TRANSMISSIONS: With the engine off, push the
transmission kickdown rod rearward until it stops and hold it in position. Push
the throttle lever rearward to its wide-open throttle position and adjust the
transmission kickdown screw to come in contact with the transmission kickdown
lever tang. WARNING: On Ford C-4 and C-6 automatic transmission vehicles only, install the
transmission kickdown adjustment screw and black retaining clip, as correctly
indicated. Failure to attend to this detail may result in a sticking wide-open
throttle or dangerous uncontrolled engine speed.
WARNING: With the engine off, recheck the assembled linkage for sticking and/or
proper return to the idle position.
|
| 15. |
Place
the air cleaner gasket (supplied) on the sealing flange, and
install the air cleaner.
|
| 16. |
With
some air cleaner configurations, it may be necessary to use an air
cleaner spacer to provide adequate clearance between the
carburetor and the air cleaner. Holley offers such a spacer
(Holley P/N 17-13). Depending on the overall height, obtain the
proper length 1/4 x 20 stud and install in the carburetor airhorn. Close the hood slowly to ensure adequate clearance between
the air cleaner stud and the hood.
|
| |
WARNING: Inadequate clearance between the air cleaner and the throttle lever
could result in throttle sticking and uncontrolled engine speed. Check the
clearance between the throttle lever and air cleaner for proper operation. Check
the clearance between the air cleaner and the hood before closing the hood
completely.
|
| |
MAINTENANCE WARNING: Fuel system components, including fuel lines and the
carburetor, should be inspected periodically to assure no fuel leakage and to
ensure the soundness of the hoses. Today’s clean emissions engines provide
higher temperatures in the engine compartment. These high temperatures promote
faster aging of non-metallic materials. |
| |
Hoses that exhibit surface cracks, when bent to 180°, should be replaced. The
presence of liquid fuel demands tightening of fittings, hose replacement, and
retorquing of the fuel system component flange nuts. Periodically check the
torque on the fuel bowl screws to 25-30 in./lbs. to assure proper fuel metering.
GENERAL: Some very important factors to optimize efficiency and performance
include: Correct engine timing, correct spark plug gap and heat range, ignition
components in good working order, and correct operation of exhaust heat valve .
|
| CHOKE ADJUSTMENT: |
| |
IMPORTANT: The TRUCK AVENGER carburetor has been factory wet-flowed and
calibrated. The “out of the box” settings should be very close for all
adjustments. The following tuning section is included ONLY to aid you in fine
tuning adjustments.
|
| 1. |
You
can control the choke operation by rotating the choke cap. If the
choke comes off too soon, loosen the three screws and rotate the
choke cap counterclockwise one notch at a time, until the choke
operation is satisfactory. Rotate the choke cap clockwise, if the
choke comes off too late. After making the final adjustments,
start the engine and make sure the choke plate opens completely.
A. A choke that comes off too soon could exhibit one or more of the following
symptoms: stalling, surging, backfiring, stumbles, or poor vehicle driveability
when the vehicle is cold.
B. A choke that comes off too late could exhibit one or more of the following
symptoms: black smoke from the tail pipe, poor drivability when cold, poor gas
mileage, misses, or rough idle.
|
| 2. |
From
the factory, the choke cap has built-in limiters. If choke
operation is unsatisfactory and you have adjusted the choke cap in
either direction to the limiters with unsatisfactory results,
recheck your positive electrical line connection.
|
| 3. |
If
the fast idle RPM is too low or too high for your preferences,
TURN THE ENGINE OFF. Advance the throttle to wide-open, exposing
the fast idle set screw below the choke housing (See Figure 8).
|
| 4. |
Using
a 1/4” open end wrench, turn the screw clockwise to increase the
RPM or counterclockwise to decrease the RPM. The factory setting
should give you a 1500-1600 RPM fast idle speed.
NOTE: All vacuum ports must be plugged at this time.
|
| |
Figure 8 |
| IDLE MIXTURE NEEDLES: |
| |
Idle mixture needles control the air/fuel mixture at idle. These have been
preset at the factory and SHOULD NOT need any adjustments. However, if you feel
that adjustment is necessary, you can use the following procedure to do so. When
tuning the idle mixture, you’re actually tuning for the best manifold vacuum.
Idle mixture needles are found on the primary metering blocks. If you change one
idle mixture needle, you must change the other idle mixture needle by the same
amount. Here are the proper steps for setting the idle mixture needles.
|
| 1. |
Attach the vacuum gauge to a manifold vacuum port on the throttle
body (Figure 7).
|
| 2. |
Adjust each idle mixture screw (Figures 9 & 10) 1/8 turn at a
time, alternating between each screw. Turn them equally, until you
achieve the highest possible vacuum reading or smoothest idle
without adjusting the curb idle speed screw. Turn screws in to
lean the mixture. Turn them out to richen the mixture.
|
| |
Figure 9 |
Figure 10 |
| 3. |
Now
that the idle mixture is set, it may be necessary to go back and
reset the idle speed using the curb idle speed screw, as shown in
Figure 11.
|
| 4. |
If a
vacuum gauge is not available, use a tachometer to obtain the
highest RPM. |
| |
Figure 11
|
| ROUGH
IDLE AND VACUUM LEAKS: |
| |
If a rough idle persists after the engine has been
started and the mixture screws adjusted, check for manifold vacuum leaks. These
could result from unplugged vacuum fittings or a carburetor flange gasket that
was torn during installation. Recheck for proper attachment of all vacuum lines
and check the lines for cracks.
If the manifold was changed, a manifold vacuum leak could occur at the cylinder
head/manifold surface due to damaged gaskets or improper torquing. Frequently,
manifold vacuum leaks occur from the valley side of the manifold. These are very
difficult to detect, unless a discernible whistle can be heard.
NOTE: In most cases, when rough idle occurs after a carburetor/manifold change,
they result from manifold vacuum leaks similar to those described above.
Assuring a proper manifold installation rather than assuming the carburetor is
not functioning properly will ultimately save time.
|
| FLOAT LEVEL ADJUSTMENT: |
| |
Primary and secondary float adjustments are set at the factory, but variations
in fuel pressure could cause a change in these settings. To aid in adjustment of
the float levels, clear sight plugs are installed from the factory. These do not
need to be removed from the bowls to make this adjustment. The following
procedure shows how to make these adjustments:
|
| 1. |
Start
the vehicle.
|
| 2. |
Observe the sight plug for the fuel level. If none is seen, the
level is too low. If it is higher than the bottom of the sight
window, it is too high. NOTE: A properly set float level will have
the fuel level located at the bottom edge of the sight window, as
shown by the line in Figure 12.
|
| |
Figure 12
|
| 3. |
To
adjust, shut down the engine.
|
| 4. |
Loosen the lock screw on top of the fuel bowl just enough to allow
you to turn the adjusting nut. Hold the screw in position with the
screwdriver.
|
| 5. |
Using
a 5/8” wrench, turn the adjusting nut in the appropriate
direction: Clockwise to lower float and counterclockwise to raise
float. Turn the adjusting nut in increments of 1/4 of a rotation.
Retighten the lock screw.
|
| 6. |
Restart the vehicle and observe the sight window.
NOTE: Rocking the truck slightly from side to side may make it easier to see the
float level through the sight window.
|
| 7. |
Repeat steps 1 through 8 as necessary.
|
| |
WARNING! Removal of the spring loaded needle and seat assembly may cause some
components to fall into the float bowl. Therefore, if the removal of the spring
loaded needle and seat assembly is ever attempted, Holley recommends removing
the float bowl first.
|
| SECONDARY FLOAT LEVELS: |
| |
Very little fuel is drawn out of the secondary fuel bowls during idle operation.
This makes it a little tricky to set the proper float level with the sight plugs
installed. Many customers attempt to adjust the rear float level down by turning
the adjusting nut clockwise, only to see the fuel level rise through the sight
plug. This is due to the float being pushed down into the fuel, therefore
displacing the fuel to a higher level. You will find it easier to adjust the
float levels, if you rev the engine slightly by opening the secondaries between
adjustments. This can be easily done by pushing upward on the secondary
diaphragm stem or by rolling the secondary throttle shaft linkage forward on the
driver’s side of the vehicle. This will use fuel from the secondary bowl at a
much faster rate, allowing the float level to seek the adjustment point that you
have set. Once the floats have been set with this procedure, drive the vehicle,
making sure the secondaries open and recheck the float level.
|
| VACUUM OPERATED SECONDARY THROTTLES: |
| |
Many people have the misconception that opening the secondary throttles sooner
will provide increased performance. Others think they must “feel” a kick when
the secondaries engage. Still others believe that they should disconnect the
vacuum diaphragm and make the secondaries open mechanically.
|
| |
Before going any further, let’s discuss these points in a reverse order. First,
if we could make our vacuum-operated secondary carburetors perform better by
opening the secondaries mechanically, it would be to our advantage to do so
since all that vacuum actuating hardware is expensive and requires much time and
money to calibrate. Mechanical secondary carburetors all utilize a secondary
pump shot to prevent bogging when the secondaries are opened. Secondly, those
who “feel” a kick when the secondaries engage are actually feeling a flat spot
during initial acceleration, because the secondaries have already begun to open
and have weakened the fuel delivery signal to the primary boosters. The engine
is struggling to increase speed and what they actually feel are the secondary
nozzles “crashing in” as the engine finally reaches the speed where it provides
the proper fuel delivery signal to primary and secondary venturi. Third, opening
the secondaries early causes the situation described above. The secondaries must
not open until the engine requires the additional air. This allows torque to
increase along the peak torque curve. Performance is compromised less by holding
the secondaries closed a little longer than by opening them a little too soon.
If the opening rate of the vacuum operated secondaries is properly calibrated
there should not be a “kick”, only a smooth increase in power should be felt.
|
| VACUUM OPERATED SECONDARY TUNING: |
| |
The secondaries will not open by free-revving the engine. The engine needs to be
under a load before they will open. If you are still uncertain if they are
opening, you can take a normal paperclip and clip it onto the secondary
diaphragm rod and slide it up against the bottom of the secondary diaphragm
housing. Go out and drive the vehicle, making sure to get into the secondaries.
When you return you will be able to look at the position of the paperclip on the
rod. If it is lower on the rod, you can tell the secondaries opened and how far
they opened. This is useful in determining if you need a heavier or lighter
secondary spring.
|
| 1. |
Remove the air cleaner assembly.
|
| 2. |
Remove the 2 Phillips screws from the black vacuum diaphragm
spring cap (Figure 15).
|
| 3. |
Lift
off the cap and spring. Remove the spring from the cap. Replace
with a softer (silver) spring, if desired.
|
| 4. |
The
silver spring will allow the secondaries to open sooner (for light
trucks) and increase performance.
|
| 5. |
The
black spring (installed at the factory) will force the secondaries to
open later (for heavier trucks) and increase fuel economy.
|
| |
Figure 13
|
Figure 14 |
| 6. |
The
black spring that comes in the Truck Avenger Carburetor kit has
been calibrated to give the best performance and fuel economy in
most applications.
|
| 7. |
Once
you have selected a spring, attach it to the cap (Figure 13) by
placing the small end of the spring over the center post on the
cap. Check the o-ring seal and place the cap and spring back into
the vacuum diaphragm housing (Figure 14).
|
| |
Figure 15 |
| 8. |
Tighten the two Phillips screws securely and reinstall the air
cleaner, as shown in Figure 15.
|
| 9. |
Test
drive the vehicle.
|
| JETTING (MAIN JETS): |
| |
Due to varied applications that a universal performance carburetor will work
with, a few tips on jetting are provided to help you understand their purpose.
|
| 1. |
Out
of the box jetting is extremely close for most applications.
|
| 2. |
Carburetors are calibrated at sea level. Decrease the jet size
primary and secondary, one number for every 2000 ft. increase in
altitude.
|
| 3. |
Holley jets are broached, flowed, and stamped according to flow
rate. NEVER drill jets, as this seriously alters flow
characteristics. Stamped numbers are reference numbers and DO NOT
indicate drill size.
|
| 4. |
In
most cases, it will be unnecessary to increase jet size more than
four numbers greater than out of the box jetting. Exceptions could
arise when the carburetor is mounted on a very large volume,
plenum-ram manifold.
|
| 5. |
Spark
plugs provide the best indication of proper jetting. Consult an
ignition manual for proper reading of spark plugs. |
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