Maverick and Comet Repair
Fuel System
Motorcraft Variable
Venturi 2700W
For 1977, Ford's new 2700W (Variable Venturi) carburetor is available on
California cars equipped with the 302 V8. Since the design of this carburetor
differs considerably from the other carburetors in the Ford lineup, a little
theory might be helpful here.
In exterior appearance, the variable venturi carburetor is similar to
conventional carburetors, and like a conventional carburetor, it uses a normal
float and fuel bowl system. However, the similarity ends there. In place of a
normal choke plate and fixed area venturis, the 2700W carburetor has a pair of
small oblong castings in the top of the upper carburetor body where you would
normally expect to see the choke plate. These castings slide back and forth
across the top of the carburetor in response to fuel/air demands. Their movement
is controlled by a spring loaded diaphragm valve regulated by a vacuum signal
taken below the Venturis in the throttle bores. As the throttle is opened, the
strength of the vacuum signal increases, opening the Venturis and allowing more
air to enter the carburetor. Fuel is admitted into the venturi area by means of
tapered metering rods that fit into the main jets. These rods are attached to
the Venturis, and, as the venturis open or close in response to air demand, the
fuel needed to maintain the proper mixture increases or decreases as the
metering rods slide in die jets. In comparison to a conventional carburetor with
fixed Venturis and a variable air supply, this system provides much more precise
control of die fuel/air supply during all modes of operation. Because of die
variable venturi principle, there are fewer fuel metering systems and fuel
passages. The only auxiliary fuel metering systems required are an idle trim,
accelerator pump (similar to a conventional carburetor), starting enrichment,
and cold running enrichment.
NOTE: Adjustment, assembly and disassembly of this carburetor require a
number of special tools which are available only from your Ford dealer. Do not
attempt to adjust or rebuild the carburetor without first purchasing the special
tools.
ADJUSTMENTS
Before making any adjustments with the engine running, set the parking brake and
block the wheels. Make sure the engine is at normal operating temperature and
that any power accessories are turned off.
Adjust the curb idle speed as you would on a conventional carburetor. Check the
emission control decal under the hood for the proper speed.
|
Year
|
Fuel Float
Level Adjustment
(in.. ± 1/32 in.) |
Fast Idle Cam
Index Setting
(in. ± 1/64 in.)
|
Anti-stall
Dashpot
Adjustment
(in.± 1/64 in.)
|
Choke Plate
Pull-down
Clearance
Adjustment
(in. ± 0.0100 in.)
|
Dechoke
Clearance
Adjustment
(minimum in.)
|
Automatic Choke
Thermostatic
Spring Housing
Adjustment
|
|
1970
|
170 eng-7/32
200 eng-3/8 |
|
7/64 |
170 engs-0.225
200 engs-0.265
|
170 eng-0.28
200 eng-0.25
|
170 man trans-1-Rich
170 auto trans-Index
all 200 eng-Index
|
|
1971
|
3/8 |
170 man trans--0.105
200 man trans--0.170
200 auto trans--0.140
|
without A/C
0.100 |
170 man trans--0.200
200 man trans--0.230
200 auto trans--0.200
|
170 eng-0.28
200 eng-0.25
|
Index
|
|
1972
|
3/8 |
170 man trans--0.105
200 man trans--0.170
200 auto trans--0.140
|
without A/C
0.100 |
170 man trans--0.170
200 man trans--0.230
200 auto trans--0.200
|
170 eng-0.28
200 eng-0.25
|
170 man trans--Index
200 man trans--Index
200 auto trans--1-Rich
|
|
1973
|
3/8 |
200 man trans--0.170
200 auto trans--0.140
|
without A/C
0.100 |
200 man trans--0.230
200 auto trans--0.200
|
0.25
|
200 man trans--Index
200 auto trans--1-Rich
|
|
1974
|
3/8 |
200 man trans--0.170
200 auto trans--0.140
|
without A/C
0.100 |
200 man trans--0.230
200 auto trans--0.200
|
0.25
|
Index
|
|
1970
|
9/16
|
0.115
|
without A/C
7/32
|
0.19
|
0.25
|
1-Rich
|
|
1971-72
|
9/16
|
0.115
|
None
|
0.19
|
0.25
|
1-Rich
|
|
1973
|
9/16
|
0.115
|
None
|
0.19
|
0.25
|
Index
|
|
1974
|
9/16
|
0.115
|
None
|
man trans--0.30
auto trans--0.19
|
0.25
|
Index ♠
|
|
1975
|
3/8 ♣
|
0.140
|
None
|
0.290
|
0.25
|
200 eng--Index
250 eng--2 Rich
|
|
1976-77
|
25/32
|
0.140
|
None
|
200 eng-0.260
250 eng-0.290 ♥
|
|
200 49 states--1 Rich
250 49 states--Index
250 California--2 Rich
|
|
Autolite
(Motorcraft)
2100D-V2
|
| Year |
Fuel Level
(inches)
|
Float
Adj.
(inches) |
Fast Idle Cam
Index Setting
(inches)
|
Anti-stall
Dashpot
Adjustment
(inches)
|
Accelerator Pump
Operating Rod
Position
(in overtraval
lever)
|
Automatic Choke
Thermostatic
Spring Housing
Adjustment
|
Choke Plate
Pull-down
Clearance
Adjustment
(in. ± 0.0100 in.)
|
|
1971
|
7/16
|
13/16
|
man
trans--0.150
auto
trans--0.130
|
without A/C
auto trans-1/8
|
man trans--#3
hole
auto trans--#2
hole
|
man - 1 Rich
auto - Index
|
man trans -
0.170
auto trans -
0.150
|
|
1972
|
7/16
|
13/16
|
.0130
|
without A/C
auto trans-1/8
|
#2A hole
|
1 - Rich
|
man trans -
0.140
auto trans -
0.150
|
|
1973
|
7/16
|
13/16
|
See Procedure
|
None
|
#2A hole
|
3 - Rich
|
|
|
1974
|
7/16
|
13/16
|
See Procedure
|
None
|
#2A hole
|
3 - Rich
|
0.160 ♦
|
|
1975
|
7/16
|
13/16
|
See
Procedure
|
None
|
#2
hole
|
3 -
Rich
|
0.140
|
|
1976-77
|
7/16
|
13/16
|
See
Procedure
|
None
|
#2
hole
|
3 -
Rich
|
0.140
|
♠ Choke cap setting on carburetor
D4DE--AAA is 1 lean
♣ Float level in 3/4 in on D5DE--NB
carburetor
♥ Pull-down clearance is 0.230 in. on
D6DE--BB carburetor
♦ Overrich choke setting -increase clearance
in steps of 0.020 in
Lean choke settings-decrease clearance in steps of 0.020 in.
COLD ENRICHMENT METERING ROD
NOTE:
This procedure requires special tools.
1. Remove the choke cap.
2. Install the stator cap (Tool T77L-9848-A) as a weight to seat
the cold enrichment rod.
3. Install a dial indicator or equivalent with the tip on the
top surface of the enrichment rod and adjust the dial to zero.
Raise the weight slightly and release to make sure the zero
repeats.
4. Remove the stator cap and reinstall it at the index position,
the dial indicator should read to specification. If the rod
height is not to specification turn the adjusting nut clockwise
to increase or counterclockwise to decrease height.
5.
Reinstall the choke cap at the specified setting
CONTROL VACUUM
1. Install a tachometer.
2. Start the engine and set the idle to specification.
3. Using an alien wrench turn the venturi valve diaphragm
adjusting screw clockwise until the valve is firmly closed.
4. Connect a vacuum gauge to the vacuum tap on the venturi valve
cover.
5. With the engine at curb idle, use an allen wrench to turn the
venturi bypass adjusting screw to reach the specified vacuum
setting.
NOTE: It may be necessary to reset the idle speed while making
the adjustment.
6. Turn the venturi valve diaphragm adjusting screw
counterclockwise until the vacuum drops to the specified
setting.
NOTE: It is necessary to cycle the throttle during this
adjustment to get the vacuum to drop.
7. Check and/or reset the curb idle.
FAST IDLE SPEED
With the engine idling,
EGR disconnected and the vacuum line plugged, make sure the fast
idle lever is on the specified step of the fast idle cam. Turn the
fast idle adjusting screw clockwise to increase speed and
counterclockwise to decrease speed.
FUEL LEVEL ADJUSTMENT
Remove the carburetor upper body. Remove the old gasket and
install a new one. Fabricate a gauge to the specified dimension.
Check the chart for this.
Turn the upper body upside down and place the fuel level gauge
on the cast surface, not on the gasket. Measure the vertical
distance from the cast surface of the upper body to the bottom
of the float. If it needs adjustment, bend the float operating
lever away from the fuel inlet needle to decrease the setting
and toward the needle to increase the setting.
CONTROL VACUUM REGULATOR (CVR) ADJUSTMENT
NOTE: The cold enrichment metering rod adjustment must be
checked and/or set before making this adjustment.
1. Rotate the choke cap 180 degrees clockwise (rich) from index
and cycle the throttle to set the fast idle speed cam.
2. Press lightly on the CVR rod. If there is any down travel,
the rod is not seated and must be adjusted. If there is no down
travel, turn the adjusting screw counterclockwise until there is
some down travel and proceed with the adjustment.
3. Turn the CVR rod clockwise until the adjusting nut just
begins to rise.
4. Again, press lightly on the CVR rod...if any spring-back can
be seen the rod is not fully seated. Turn the adjusting screw
clockwise in 1/4 turn increments until no spring- back can be
seen.
5. Reset the choke cap to the specified setting.
Repair
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