Ford VV (variable venturi) carburetor
Idle speed: 800 ± 25 rpm
Idle mixture (CO content): 1.5 ± 0.5%
||A Throttle spindle
B Mixture screw
C By-pass leak adjuster
E Needle valve
F Main jet body
G Metering rod
H Air valve
J Automatic choke unit
K Bi-metal coil
L Carburettor control diaphragm
M Accelerator pump diaphragm
1 Air valve
2 Metering rod
3 Carburettor control diaphragm
4 Adjustment screw
6 Connecting channel
7 Connecting levers (linkage)
9 Throttle lever
10 Anti-dieselling valve
11 Accelerator pump
12 Vacuum piston
13 Automatic choke
14 Needle valve
15 Main fuel jet
Main fuel system
1 Ventilation channel
2 Main fuel jet
3 Metering rod
4 Air valve
7 Fuel feeding pipe
9 Fuel vapour
Normally the diaphragm (8) is pulled down by the vacuum after the throttle resisting the force of the spring (7). The valve (1) is closed.
3 Ventilation (the arrow is flipped)
4 Air hole
5 Accelerator pump injector
6 Vacuum chamber
8 Accelerator pump diaphragm
9 Fuel chamber of the pump
The fuel chamber (9) fills with fuel from the float chamber through the valve (2). When accelerating the vacuum after the throttle decreases so the spring (7) pushes the diapragm (8), delivering fuel through the valve (1) to the accelerator pump injector (5). The air hole (4) does not allow sucking of fuel from the accelerator pump at high speeds.
Through the ventilation channel (3) fuel vapour from the accelerator pump goes back to the float chamber. So the fuel chamber (9) is always filled with cold fuel.
When the engine stops the vacuum after the throttle is gone and the spring (7) pushes the fuel from the chamber (9) to the injector (5). For easier consecutive start of the engine is recommended to partially open the throttle.
Carburettor (Ford VV type) - removal and refitting
Note: A new gasket must be used when
refitting the carburettor. A tachometer and an
exhaust gas analyser will be required to check
the idle speed and mixture on completion.
1 Disconnect the battery negative lead.
2 Remove the air cleaner.
3 Relieve the pressure in the cooling system
by unscrewing the expansion tank cap. If the
engine is warm, place a thick rag over the cap
and unscrew the cap slowly as a precaution
against scalding. Refit the cap after relieving
4 Identify the automatic choke coolant hose
locations, as an aid to refitting, then
disconnect the hoses (being prepared for
coolant spillage.) Either plug the hoses or
secure them with their ends facing upwards to
prevent loss of coolant.
5 Disconnect the wiring from the antidieselling (anti-run-on) valve.
6 Disconnect the fuel hose and vacuum pipe. Plug the end of the fuel
hose to minimise petrol spillage.
7 Disconnect the throttle cable from the
carburettor throttle lever (see illustration).
8 Remove the two securing nuts and
washers, and lift the carburettor from the inlet
manifold studs (see illustrations). Recover
9 Refitting is a reversal of removal, bearing in
mind the following points.
10 Ensure that the mating faces of the inlet
manifold and carburettor are clean, and use a
11 Ensure that the coolant hoses, fuel hose,
and vacuum pipe are correctly routed and free
from restrictions. If any of the hoses were
originally secured with crimped type clips,
discard these and use new worm drive clips
12 On completion, check and if necessary
top-up the coolant level. Check and if
necessary adjust the idle speed and mixture.