Ford VV (variable venturi) carburetor


Specifications:
Idle speed: 800 25 rpm
Idle mixture (CO content): 1.5 0.5%

Exploded view of Ford VV carburetor A Throttle spindle
B Mixture screw
C By-pass leak adjuster
D Float
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
5 Spring
6 Connecting channel
7 Connecting levers (linkage)
8 Hole
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

Main fuel system 1 Ventilation channel
2 Main fuel jet
3 Metering rod
4 Air valve
5 Venturi
6 Throttle
7 Fuel feeding pipe
8 Float
9 Fuel vapour

Accelerator pump

Accelerator pump 1 Valve
2 Valve
3 Ventilation (the arrow is flipped)
4 Air hole
5 Accelerator pump injector
6 Vacuum chamber
7 Spring
8 Accelerator pump diaphragm
9 Fuel chamber of the pump
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.
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.
Removal
1 Disconnect the battery negative lead.
2 Remove the air cleaner.
Disconnecting the throttle cable from the throttle lever - Ford VV carburettor 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 the pressure.
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 the gasket.Remove the securing nuts and
washers . . .  . . . and lift the carburettor from the inlet manifold - Ford VV carburettor

Refitting
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 new gasket.
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 on refitting.
12 On completion, check and if necessary top-up the coolant level. Check and if necessary adjust the idle speed and mixture.

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