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The Ford Capri Laser Page

Carburettor Overhaul

This section describes the procedure for dismantling and overhauling a Weber 32/36 carburettor as fitted to most 2lt pinto powered Capris. The overhaul kit contains all the bits you will require to to the job and is available from the Capri Club or alternatively from a good parts supplier.  A useful guide in pdf format can be downloaded here

Carburettor Removal

The first job is to get the carburettor off the car which is not too hard. Firstly you should disconnect the battery terminals as we don't want any sparks whilst there is petrol vapour in the air. The air filter should be removed from the car to reveal the carburettor sitting on the inlet manifold. The carburettor has several pipes attached to it which need removing. It is worth labeling everything as you go so there is no confusion later. These are as follows:

The fuel lines: There are two fuel lines, the inlet pipe rises up from the fuel pump that is bolted on the side of the engine next to the distributor, and the outlet pipe that goes all the way back to the petrol tank. These two hoses are connected to the front of the carburettor and should be removed by carefully undoing the small jubilee clips and prising off. No petrol will come pouring out but it is still a good idea to bung up the ends with something.

The vacuum advance / retard pipe comes out of the side of the carburettor next to the rocker box and snakes its way down to the distributor. This hose should simply pull off.

The low vacuum enrichment (LOVE) valve hoses. This may be a bit different on your carburettor but on mine these two hoses are attached to a green coloured plug on the underside of the inlet manifold referred to as the Ported Vacuum Switch (PVS) . The water temperature around the inlet manifold controls the opening and closing of the PVS. The ends of the hoses push onto the two pipes in the front RHS corner of the carburettor. Again these hoses just pull off but make a note of which way round they go.

The automatic choke. If your Weber has an automatic choke bolted on the side of the carburettor it will be fitted with water hoses from the cooling system attached with hose clips. You will need something to catch the water when you pull them off and again I would bung them up to stop more fluid loss.

With all these disconnected the next job is to disconnect the throttle connection at the back. It may be easier if you undo the bolts that hold the throttle cable housing place. Somewhere along the linkage is a U-shaped clip device which if you play with it you will be able to disconnect from the carburettor. The carburettor is now ready to be removed from the car by unbolting the four nuts in each corner. These are of varying difficulty to get to and you will find it easier if you use an open-ended spanner. Keep all the washers and nuts in a safe place and gently lift the carburettor off the studs. It may need a bit of gentle twisting to remove as there are gaskets in place.

At the base of the carburettor you will find a spacer gasket which is a rectangular block approximately 5mm thick. Top and bottom of this should be a thin card gasket that seals everything in place. You can buy a new spacer with gaskets fitted for around £5 from Ford. Alternatively you can clean up the spacer with a sharp knife and buy two new card gaskets instead.

With the carburettor out of the car, the first thing to do is give the outside a good clean. I used a large tray with white spirit and cleaned it up with an old toothbrush, then dried it with plenty of 'blue roll'. If you hold the carburettor upside down then all the remaining petrol inside should pour out as well.

Carburettor dismantling

Do this bit at a table with plenty of newspaper. The carburettor is in two halves which are fixed together by six screws visible on the top plate. Before the two halves will separate you will need to disconnect the arm that is attached to the end of the choke plate spindle. It has a small circlip fitted to it, which you can prise off with a small screwdriver. Watch it carefully a it may ping off onto the floor. Have a small dish ready to put all the small parts in!

Undo the six screws and pull the top off the carburettor. The two halves are joined with a card gasket that is included in the overhaul kit. When you turn it upside down you will see the two brass floats. If you inspect the spindle area you will see that the floats control a needle valve that is included in the overhaul kit. First thing to do is to remove the floats by sticking a small screwdriver in the slot where the float spindle is and twisting it to prise it open slightly. As you do this push the spindle out using another small screwdriver. The spindle should be put somewhere safe. You can now simply lift the floats away from the main body.

With the floats removed you can unscrew and remove the brass needle valve assembly and replace it with the new one that comes in the kit. You will see that it has a small rubber tipped needle that stops the petrol from overfilling the carburettor. The new one in my kit was not identical to the old but it is pretty obvious how to reconnect it to the floats.

 Just in front of the float valve is a power valve device that is a tall metal rod attached to the carburettor by three screws on a triangular foot. Undo these crews and carefully lift away the rod. You will see that the end of it has a triangular plastic membrane that is held in place by the three screws. This should be intact without holes or tears. If it is it needs replacing but note that it is not included in the service kit.

To replace this rod press down on the spring to stop the membrane stretching as you refit the three screws. You can test this power valve by holding your finger over the small hole on the side of the metal housing and pressing down on the rod. The rod should pop back up slowly as there is now a slight vacuum behind the membrane.

One final thing to do before moving on to the lower half is to replace the fuel filter that is located behind the large brass nut that sits below where the fuel comes into the carburettor.  Undo the brass nut with a spanner and the fuel filter will simply drop out of its hole.  There should be a new one of these in the overhaul kit.  Also replace the copper sealing washer fitted on the nut with a replacement supplied.

The second pump on the front of the carburettor, towards the choke housing, is the accelerator pump and this simply squirts additional petrol into the carburettor during acceleration. It is operated by the throttle via a metal linkage. Try rotating the throttle spindle to see it working. Again the pump is a direct replacement for the old one and is reached by unscrewing and detaching the four screws on the cover plate of the pump.  The pump will simply come away from the housing and has a spring behind it.  Do not loose the spring in your enthusiasm to remove the pump.  Make sure you use the replacement gasket in the the overhaul kit when refitting.

That is basically all you need to do to service the carburettor. Next job is to set the float height. The float height is measured by holding the top part of the carburettor vertically and measuring the distance from the top of the housing (where the gasket goes) to the bottom of the float. This gives the upper resting dimension and should be 35mm on a 2lt and 28mm on a 1.6lt. This can be adjusted by gently bending the metal tabs on the float hinge a little.  Now repeat the measurement this time with the upper body held horizontally.  This should be 51mm on a 2lt and 35mm on a 1.6 and can be adjusted by bending with the inner tag a little.  These adjustments are important because they govern the height of the petrol in the float chamber: too little and the car will hesitate around bends and too much and unwanted petrol will flood into the engine.

With the floats all set correctly it is time to put the two halves of the carburettor back together using a new gasket supplied in the kit. The two halves should come together easily and you can refit the six retaining screws. It's up to you if you want to use some gasket sealant but you must be careful to use it sparingly and make sure none of it ends up blocking vital holes. You then need to reattach the choke flaps to the spindle using the original circlip.

If you have an automatic choke fitted then this will require a bit of attention. The easiest way to understand how it works is to open and close the throttle slowly and you will see the cam mechanism turn the fast idle speed on and off. The choke itself is governed by two things: a bi-metallic coil that sits in the housing connected to the water pipes, and a vacuum device that is on a spindle sticking out backwards and terminating in a triangular metal cover.

The choke housing can be rotated slightly to adjust the effect of the bi-metallic strip. You will see a metal collar attached with three screws. Before you undo these make sure that there is a mark across the housing so you can re-set it later. The bi-metallic strip is accessed by undoing the three screws and removing the metal choke cover. There is a plastic heat shield cover over the chamber and underneath is the strip itself. It is a coil of metal with a pin on the end which passes through a slot and attaches itself to the choke flaps. So you can see that the coil moves with the temperature of the water passing over the back and as it does the movement is used to open and close the choke flaps at the top of the carburettor. When cold these flaps should be almost fully closed and when fully hot they should be vertical. All they do is restrict the airflow into the carburettor and thus enrich the fuel content. When fully open they are not doing anything to the airflow and the choke is off.  All very simple!

Make sure that all the chambers are clean and the bimetallic strip is free to twist. The next part of the choke is the vacuum pull-down device which is located behind the inner plastic cover. You will see that the spindle passes out of the chamber towards the triangular metal housing which holds the vacuum diaphragm itself. If you unscrew the cover of triangular cover there is another membrane (not included in the kit). Make sure that this is free of splits and in good working order. It is connected to the choke via a spindle with a spring loaded slider on it.  If you take a small screw driver you can slide the mechanism along the spindle to the stop and you will see that the choke flaps will drop downwards so there is a gap of approximately 7mm between the end of the flap and the side of the chamber.  If it is not 7mm (test it by sliding a 7mm drill bit down - it should just clear the gap) you can adjust the stop position by inserting a small screwdriver into the centre of the triangular end cap (there may be a blanking plug fitted that can be prised out) where you will find an adjuster screw.  As you turn this the 'maximum vacuum pull down' will change.  Adjust to give 7mm.  Refit the blanking plug and carefully reassemble the choke assembly.  If this section sounds like a complete nightmare - don't worry because it is very unlikely that you will actually need to adjust anything.

With the choke all sorted out, it is time to refit the carburettor to the manifold.  It sits on the spacer which must have two new paper gaskets fitted top and bottom.  Use a slither of blue gasket sealant to get a good fit.  Make sure that the spacer is fitted the correct way round as it is not symmetrical.  Lower the carburettor on to the gasket and carefully refit the four nuts and washers.  Tighten these down in sequence until they are nice and tight.

With the carburettor refitted it is time to reattach the throttle linkage, the fuel lines, the vacuum hoses and the water hoses.  The linkages should be treated to a bit of fresh grease.  She is ready to fire up but make sure that your battery is good because you will need to turn the starter over for several seconds to get some petrol into the float chamber.

The next job is to set the choke phasing.  This is the set of springs and cams that sits between the carburettor main body and the choke housing.  As you manually open the throttle slowly you will see that the fast idle screw adjuster is set onto the cam and it stays there when you release the throttle.  This is how you start the car - push the accelerator once to set this cam in place.  When the car starts you should have about 2000rpm on the fast idle.  This can be adjusted by turning the screw that sits on the cam.  It can only be done with the car engine running.  Once the accelerator pedal is 'tapped' the cam disengages and the choke will take over giving a faster tick over than normal (say 1100rpm).  The fast idle only comes on if you push the accelerator pedal to the floor before starting with your feet off the pedals.  As the water gets hotter the bimetallic strip starts to rotate and the choke flaps start to rise vertically.  The rpm will slowly drop so that when the engine is up to temperature the tick over is about 800rpm.  If the engine is hot and you want to restart the car then don't push the pedal to the floor this time - just depress the accelerator half way as you turn the key.  she should fire up after a few turns.  It is very important to start your Capri using the correct procedure otherwise the choke is not properly engaged when cold!

With that job out of the way we can concentrate on the lower half of the carburettor. The main jets are located underneath the two brass screws in the middle section. These sit in small copper washers that are supplied in the kit and should be replaced. If you unscrew these and remove, you will be able to see the jets sitting in the pipe. The jets themselves should be OK but you can remove them by blowing some compressed air down the pipe; the jets should simply pop up out of their hole. Give them a good blast with compressed air to make sure the emulsifying tubes are clear and return them to their pipes.

There are two additional pumps fitted to the carburettor that have replacement membranes in the overhaul kit. On the front of the carburettor on the RHS is the LOw Vacuum Enrichment (LOVE) pump which supplies an extra squirt of fuel into the carburettor if the engine is about to stall (ie when the vacuum is low in the manifold). In essence it is an anti-stall device. It can be dismantled simply by undoing the four screws that hold the cover in place. Simply remove the cover and pull the old pump membrane off. The replacement is simply fitted in its place and the cover reattached with a new gasket from the overhaul kit.

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