Section K (26/12/08 )

FUEL SYSTEM

K.1    General
K.2    Removal of the fuel tank
K.3    Removal of the fuel gauge float unit
K.4    Removal of the filter tube assembly
K.5    Removal of the fuel strainer
K.6    The fuel pump
K.7    Air cleaner
K.8    The carburettor (Stage I)
K.9    Description and operation
K.10   Carburettor adjustments
K.11   Overhauling the carburettor
K.12   The carburettor (Stage II)
K.13   Tuning and fitting instructions
K.14   Specifications and repair data

 

Sabra Handbook Fuel System Plate 09

     

Kl 

The 81/2 gallon capacity fuel tank is situated at the rear of the chassis and is secured by straps to the rear of the chassis underside. Delivery of the fuel is effected by a mechanically driven pump drawing fuel from the tank through a filter tube assembly and flexible nylon pipe to a petrol strainer mounted on the engine bulkhead. Fuel content is measured by a float-operated variable resistance located in a well on the tank upper surface; the resistance is transmitted to the fuel contents gauge mounted on the facia panel. 

K2 

Removal of the Fuel Tank 

Jack up the vehicle and drain off petrol at drain plug. Disconnect tank inlet pipe from flexible hose by removing Jubilea clips and disconnect fuel gauge wiring at the float unit; access to these items is through the luggage boot, a small inspection plate being removed to expose the float unit beneath. Unscrew the two nuts securing the strap trunnions to the chassis cross member, collect the nuts and two retaining plates. When the tank is removed, the straps can be left attached by their bolts and nuts to the rear chassis cross member. 
To refit or renew a tank, reverse the above operations. When refitting ensure that the felt packing is in position between the tank and chassis frame and between the tank and the straps. After the tank has been positioned, strap adjustment is taken up on the strap trunnions. When refitting the drain plug, ensure that the fibre washer is clean and undamaged. 

K3 

Removal of the Fuel Gauge Float Unit 

With the fuel gauge electrical wiring previously disconnected, remove six retaining screws and lift out float unit with cork gasket. Care must be exercised not to bend or strain the float lever or dent the float. When refitting the float unit, check that the cork gasket is clean and undamaged prior to coating with jointing compound. Position the float unit in the tank and secure with six screws ensuring that the joint between the tank and the fuel unit is fuel tight. 

K4 

Removal of the Filter Tube Assembly 

Unscrew assembly from the tank, exercising care with filter end to prevent damage. Collect flbre washer. When refitting the assembly ensure that the fibre washer is clean and undamaged. Tighten down and secure to ensure a fuel tight joint. 

K5

Removal of the Fuel Strainer

Disconnect fuel pipes from the tank and fuel pump at the fuel strainer, with nine fixing clips to the right hand side of the chassis. 

NOTE: Whenever fuel pipes are disconnected, the ends must be sealed to prevent the ingress of dirt or moisture. 

K6 

THE FUEL PUMP 

The fuel pump is mounted on the right hand side of the engine, adjacent to the oil filter, and is driven by means of a rocker arm from an eccentric on the camshaft. 

Operation of the Fuel Pump 

On rotation of the engine, the eccentric on the camshaft pivots the fuel pump rocker arm and link, and pulls the diaphragm downwards against the pressure of the return spring. This creates a partial vacuum in the pump chamber, causing the inlet valve to open and draw fuel from the tank through the pipe line and the glass sediment bowl. Any sediment in the fuel is deposited in the glass bowl, being filtered by the gauze in the top of the sediment bowl before passing on to the fuel pump. 
Further movement of the camshaft eccentric allows the rocker arm to return and the diaphragm is pushed up by the return spring, causing the inlet valve to open. The fuel is then forced through the pump to the carburettor (or car- burettors in the case of the Stage II version). When the fuel in the carburettor bowl raises the float sufficiently to close the needle valve, a back pressure is created in the pump charnber, which prevents the diaphragm being pushed up by the return spring, until the needle valve opens again. 

Sabra Handbook Fuel System Pic 02

     

During the time that the diaphragm is held down by fuel pressure, the rocker arm idles on the eccentric without operating the link. 

Cleaning the Fuel Filter Screen 

The glass sediment bowl and filter (mounted on the front bulkhead, Left Hand Drive only) should be removed and washed in petrol every 5,000 miles (8,000 km.). 

To Remove and Replace 

1. Slacken off the clamp screw at the base of the sediment bowl, move the retainer clip aside and detach bowl, filter screen and cover gasket. 

2. When replacing the filter screen, ensure that it seats in its housing correctly, and also that the cover gasket fitted between the sediment bowl and the body is in good condition, as an air leak at this point may cause failure of the fuel supply. If in doubt, fit a new cover gasket and tighten the clamp screw securely. 

3. Complete removal of the sediment bowl can be effected by the removal of the two bolts and Oddie nuts securing the bowl to the bulkhead. 

NOTE : There is no sediment bowl on the R.H. Drive car and the fuel supply is fed direct from the tank to the AC fuel pump. 

Testing the Fuel Pump 

Provided there are no air leaks or obstructions in the fuel lines, a quick check on the pump can be made, as follows: 

1. Disconnect the fuel pump from the carburettor pipe at the pump outlet or the carburettor union. 

2. Crank the engine, using the starter motor, when there should be a well-defined surge of fuel for each revolution of the camshaft. If the pump does not operate correctly, check the inlet depression and delivery pressure, using suitable gauges. 

Fuel Pump Inlet Depression Test 

1. Fill the float chamber with petrol. 

2. Disconnect the fuel pump flexible pipe from the pump inlet and connect a vacuum gauge to the inlet union. 

3. Start the engine and allow it to run at an idling speed, when the vacuum reading should be at least 10 in. (25,4 cm.) of mercury. 

4. Stop the engine, when the gauge needle should take at least one minute to drop back to zero. 

Fuel Pump Delivery Pressure Test 

1. Fill the float chamber with petrol. 

2. Disconnect the fuel pump to carburettor pipe and connect the pressure gauge to the pump outlet. 

 

3. Start the engine and observe the pressure when running at idling speed. Momentarily race the engine and observe the pressure. This should not be less than 11 lb./sq. in. (0,10 kg./sq. cm.) and not more than 3 lb./sq. in. (0,21 kg./sq. cm.) at any speed. 

Fuel Pump Removal and Replacement 

To remove: 

1.    Disconnect the fuel inlet and outlet pipes. 

2.    Unscrew the two nuts securing the pump to the cylinder block and detach the pump. 

3.    Remove pump gasket. 

To replace : 

1.    Locate new gasket on pump mounting flange studs. 

2.    Refit the pump to the cylinder block studs, passing the rocker arm up between the camshaft eccentric and the wall of the crank case. Replace the two securing nuts and spring washers and tighten to 12 -> 15 Ib. ft. (1,66 -> 2,07 kg. nm.). 

3.   Reconnect the fuel inlet and outlet pipes to their respective unions on the pump and tighten securely. 

K7

AIR CLEANER

To carry out normal servicing, remove the three securing bolts and one nut. The cleaner can then be removed from the car. Unscrew the, filter bowl, empty out the old oil, clean out thoroughly and refill with fresh oil to the indicated level. Reassemble and fit to the carburettor. Sabra Handbook Fuel System Pic 03

     

K8

THE CARBURETTOR (STAGE I) 

The Stage I carburettor is of the single-venturi vertical downdraught type. It incorporates an accelerator pump to ensure rapid acceleration, an economy device controlled by manifold depression is incorporated in the carburettor body to improve petrol consumption at higher speeds, and a choke valve of the strangler type for cold starting. 

K9

DESCRIPTION AND OPERATION 

  1. Starting System 
    A rich mixture is required for starting. The choke valve is shut by means of the instrument panel control; the carburettor linkage partially opens the throttle plate. As the engine is rotated by the starter motor, a high depression is created upon the emulsion block discharge beak, see Fig. 3, and fuel is thus drawn from the capacity well in the emulsion block. When the engine is running with the choke shut, the depression created in the manifold at low speed causes the spring-loaded choke plate, which is offset on its spindle, to open, thereby admitting sufficient air to keep the engine running.

  2. Idling System (see Fig. 4) 
    When the throttle plate is in the idling position, the fuel is supplied by the slow running jet. This jet is fed through a passage from the metered side of the main jet which is located at the base of the emulsion block. The fuel is emulsified by air admitted through the air bleed hole in the main air intake and the bleed hole positioned immediately above the idling jet. The resulting mixture is drawn down the vertical channel in the carburettor body to the idling discharge hole just below the throttle plate, and thence into the induction manifold. The quantity of mixture passing through the idling discharge hole is regulated by the needle-type volume control screw. (See Carburettor Adjustment). The small hole in the carburettor body above the idling discharge hole also communicathes with the supply channel and serves to provide a smooth and progressive supply of mixture as the throttle plate is gradually opened. 

  3. Main System (see Fig. 3) 
    As the throttle plate continues to open, the engine depression at the emulsion block beak draws fuel from the capacity well in the emulsion block and the channels above the main and compensating jets. At the same time, air is admitted by the 'full throttle' air bleed (which remains permanently open) and also, if operative, by the 'part throttle' air bleed which is controlled by the economy diaphragm valve, see Fig. 4. The resulting mixture of fuel and air is drawn from the emulsion block beak into the induction manifold.

 

As the petrol level in the main jet channel falls, a number of small holes in the side of the channel are progressively exposed, see Figs. 3 and 4. This admits an increasing quantity of air into the system, thus maintaining the correctly balanced fuell-air ratio of the mixture. 

Economy Device (see Fig. 4) 

At the side of the carburettor body is a small casting attached by three screws. Inside is a diaphragm valve, which is normally held in a flexed condition by a compression spring. From the spring compartiment a small drilling gives direct communication with the engine side of the throttle plate through internal channels. 

Under 'part-throttle' cruising conditions, the manifold depression is high. This depresssion is imposed on the spring-loaded side of the diaphragm, thereby lifting the valve from its seat and so increasing the ventilation via the 'part-throttle' air bleed to the jets, thus weakening the mixture. 

When the depression in the manifold is low, the valve remains on its seating under the influence of the spring. The air supply to the jets is consequently limited to the permanent restriction of the 'full throttle' air bleed. The action of the economy device is entirely automatic and is controlled by the demands of the engine. 

Accelerator Pump System (see Fig. 5) 

The purpose of the accelerator pump is to prevent any hesitation when suddenly accelerating by providing a controlled and metered supply of fuel into the carburettor venturi coincident with the sudden opening of the throttle plate.

Sabra Handbook Fuel System Pic 04

     
Sabra Handbook Fuel System Pic 05

When the pump piston is at the top of its stroke, the pump chamber is charged with fuel admitted from the float chamber through the non-return valve at the base of the chamber. When the throttle is suddenly opened, the piston is forced down by the throttle linkage and discharges a stream of petrol through the nonreturn valve located at the top of the float chamber body, and through the horizontal discharge nozzle into the main air stream. The pump piston is returned to the charged position by the piston spring and is then ready for the next stroke. The travel of the piston, and consequently, the volume of fuel discharged at each stroke can be set in one of two positions. (See 'Carburettor Adjustments.") 

K10 

CARBURETTOR ADJUSTMENTS 

(a) Slow Running Adjustment (see Fig. 6)
To obtain the best slow running adjustment, the engine should be tuned against a vacuum gauge connected to the inlet manifold at the point where the connection is taken for the vacuum pump. Before commencing adjustment, check the air cleaner to ensure that the element is clean and, in the case of the oil bath cleaner, that the oil is clean and at the correct level.
Run the engine to allow it to warm up. To adjust the slow running, screw in the throttle stop screw until a fast idling speed is obtained, then turn the volume control screw either clockwise or anti-clockwise to obtain the maximum vacuum reading. Readjust the idling speed as necessary, and continue the adjustment until the maximum possible vacuum reading is obtained with a reasonable slow running speed. 

  Sabra Handbook Fuel System Pic 06

When a suitable vacuum gauge is not available, the engine should be warmed up and the throttle stop screw turned clockwise so that the engine is running at a fast idling speed. Screw the volume control screw in or out until the engine runs evenly. Now readjust the throttle stop screw if the engine is running too fast, followed by a further readjustment of the volume control screw. These operations should be repeated until the idling speed is satisfactory. It may be necessary to readjust the ignition setting.

Sabra Handbook Fuel System Pic 07

     

 

(b) Accelerator Pump Stroke Adjustment
The accelerator pump stroke can be adjusted by altering the position of the stop fitted under the operating arm in the top of the float chamber. In warm or temperate climates set the stop so that the operating arm will contact the large boss to give a short pump stroke. In cold climates set the stop so that the arm contacts the small boss allowing a long pump stroke. To adjust the stop, lift it clear of the float chamber against the tension of the spring and turn it through 180 (sec Fig. 7). 

A felt seal is incorporated in the top carburettor body below the adjusting collar. 

 

(c) Choke Adjustments 

The choke control cable is adjusted at the choke lever plate trunnion so that there is approximately 1 in. (3,18 mm.) free play in the cable when the control is pusbed in fully. The correct degree of throtthe opening when the choke plate is closed for starting is obtained by placing a 0,914 mm. drill (No. 64) between the edge of the throttle plate and the carburettor body at right angles to the throttle spindle. This setting can alternatively be obtained by screwing in the throttle stop screw approximately six turns from the position at which it just abuts the throttle plate stop when the throttle is fully closed (it will be necessary to remove the throttle stop screw spring for making this adjustment as the spring becomes 'coil-bound'). Then adjust the length of the choke link so that the choke lever plate is in the fully closed position.

 

 

(d) Float Adjustment 

To check the fuel level it is necessary to remove the float chamber. Operate the starter motor (ignition off) to fill the float chamber to its correct level. Remove the four bolts securing the float chamber to the carburettor body and carefully detach the float chamber. With the float in position the petrol level should be 7/8 in. (22,5 mm.) below the top face of the float chamber. If the float is removed, the petrol level will fall and should then be 1-5/16 in. (33 mm.) below the top face. 

If the petrol level is low the float arm should be bent upwards or bent downwards if the level is too high.  After adjusting the float arm, refit the float chamber and re-check the petrol level as before. 

 K11 

OVERHAULING THE CARBURETTOR 

To Remove 

1.    Remove the air cleaner. 

2.    Disconnect the choke control cable at the choke lever plate and slacken the clamp on the choke cable abutment bracket. 

3.    Disconnect the throttle at the upper end of the throttle lever connecting rod. 

4.    Unscrew the fuel pipe union. 

5.    Disconnect the distributor vacuum pipe at the rubber connection on the right-hand side of the carburettor. 

6.    Unscrew the carburettor flange nuts and spring washers and remove the carburettor. 

Sabra Handbook Fuel System Pic 07

     

To Dismantle 

  1. Unscrew the four bolts retaining the float chamber to the carburettor body and detach the float chamber. 

  2. Release the grub screw securing the connecting link between the choke valve control lever and throttle spindle. Unscrew the bolt securing the choke valve control lever to the carburettor body and detach the lever and spring. Remove the screw and lockwasher retaining the choke cable abutment bracket to the carburettor body. 

  3. Unscrew the nut and lockwasher securing the throttle lever to the spindle, pull off the throttle lever, accelerator pump operating lever, and idling lever. 

  4. Remove the pivot holt from the accelerator pump operating lever and detach the two halves of the lever and the connecting spring link. Note that a flat washer is fitted on each side of the operating lever. Pull the accelerator pump adjustment stop out of the top of the float chamber. 

  5. Unscrew the three bolts securing the economy valve housing to the carburettor body. Remove the housing, spring and diaphragm assembly. Note that gaskets are fitted on each side of the diaphragm assembly. 

  6. Unscrew the needle valve and its metal seating washer from the carburettor body. 

  7. Remove the two screws retaining the choke valve to the spindle, withdraw the spindle and detach the return spring. 

  8. Remove the two screws securing the butterfly to the spindle, pull out the butterfly and withdraw the spindle. 

  9. Straighten the tab of the locking washer under the head of the choke tube retaining screw, remove the screw and detach the choke tube. 

  10. Remove the float hinge bracket and float from the float chamber, unscrew the two bolts securing the emulsion block to the float chamber and detach the emulsion block (see Fig. 8) The following jets are mounted in the emulsion block and can be removed by unscrewing: the main jet, compensating jet, compensating well air correction jet, idling petrol jet and idling air correction jet (see Fig. 9).
    Remove the screw retaining the accelerator pump operating plunger and withdraw the plunger and spring. The accelerator pump inlet valve assembly can be removed from the bottom of the well after removal of the plunger and spring. Remove the accelerator pump outlet ball valve and unscrew the discharge jet from the face of the float chamber. 

To Reassemble 

1.    Refit the choke tube and secure it in place with the retaining screw. Ensure the end of the screw correctly locates in the hole in the choke tube, fully tighten the screw and bend one tab of the lockwasher to retain it in position. 

 
  1. Fix the throttle spindle in position so that the large flat faces towards the mixture control screw. Refit the butterfly, securing it in place with the two retaining screws. Fully tighten the screws and lightly centre punch the ends of the screws to retain them in position. Fit the choke valve spindle in position and ensure that one end of the operating spring locates in the carburettor body and the other end locates in the operating arm. Fit the choke valve in position with the larger offset portion towards the carburettor and fit the two retaining screws. Fully tighten the retaining screws and lightly centre punch the ends of the screws to lock them in position. 

  2. Fit the seating washer to the needle valve and screw the needle valve into the carburettor body. 

  3. Replace the economy valve assembly, checking that the valve seat is in good condition. Carefully check the diaphragms to ensure that they are not porous and locate the gasket on either side of the diaphragms with the holes in line. Position the assembly on the carburettor body, locate the diaphragm spring in the valve housing and secure the assembly to the carburettor with three screws. 

  4. Fit the accelerator pump adjustment stop to the carburettor body, locate a flat washer on either side of the accelerator pump operating levers and secure the assembly to the carburettor body with the pivot bolt. 

  5. Locate the choke control cable abutment bracket on the dowel of the carburettor body and secure it in place with a screw and flat washer. Locate the retracting spring on the boss on the choke operating lever and secure the lever to the carburettor with a hexagonheaded bolt. Ensure that the inner end of the retracting spring is located beneath the abutment bracket and the outer end against the lower leg of the operating lever. 

  6. Fit the idling lever to the throttle spindle, screw the accelerator pump operating lever on to the connecting link and locate the lever on the throttle spindle. Fit the throttle lever to the spindle and secure it in place with a lockwasher and nut. 

  7. Fit the connecting link between the idling lever and choke control lever, fit the choke control in the closed position and connect the link so that in this position the butterfly is slightly open. 

  8. Fit the accelerator pump inlet valve to the bottom of the operating cylinder, locate the operating spring inside the operating plunger and fit the plunger in position, securing it in place with the retaining screw. Screw the accelerator pump outlet ball valve assembly into the float chamber and the accelerator pump discharge nozzle into the face of the float chamber

  9. Refit the jets to the emulsion block, locate a gasket on the front face of the emulsion block and secure it to the inside of the float chamber with two screws. Refit the float and hinge bracket. Refit the float chamber to the carburettor body securing it in place with four bolts. 

     

To Replace 

1.    Locate a new gasket on the manifold flange and replace the carburettor with the float chamber to the front. Refit the spring washers and nuts on the mounting studs and tighten them securely. 

2.    Reconnect the distributor vacuum pipe to the rubber connection on the right-hand side of the carburettor. 

3.    Refit the fuel pump pipe and tighten the union. 

4.    Refit the throttle control rod to the upper end of the throttle lever connecting rod. 

5.    Connect the choke control cable (at the rear of the carburettor) and tighten the clamp. Pass the cable inner wire through the choke lever plate trunnion and tighten the clamping screw. Check that the choke opens and closes correctly, and that there is slight play in the cable. 

6.    Refit the air cleaner. 

K12 

THE CARBURETTORS (STAGE II) 

Conversion to give Stage II performance can be effected, calling for the substitution of twin S.U. Carburettors for the Single Zenith downdraught unit. 

 

K13

TUNING 

Fitting Instructions (Twin Carburettor Assembly) 

  1.  Disconnect throttle and choke at carburettor. 

  2. Remove existing carburettor complete with manifold.

  3. Fit the two special studs provided in the two upper threaded holes of inlet flanges on the cylinder head. 

  4. Fit the new inlet assembly using the new flange gaskets provided. 

  5. Fit the two exhaust manifold retaining clips provided in place of the original hot spot casting. 

  6. Remove the small brass 1/8 in. gas plug from the original manifold and refit into new manifold. 

  7. Cut original fuel pipe in a position determined by the length of pipe provided with new assembly and connect with rubber fuel pipe provided. 

  8. On R.H.D. models, it is necessary to lengthen the throttle arm protruding from the bulkhead by approximately 3 in. For this purpose an extension is provided in the kit and this must be brazed or welded to the existing arm. On L.H.D. models this is not necessary.

 
  1. Connect up the throttle using the threaded rod and ball ends provided, after having cut the rod to a length suitable for correct operation of the throttle, depending upon whether the vehicle is Left or Right Hand Drive. 

  2. Ensure that full throttle can be obtained and that it also returns to fully closed position. Connect up choke control. Tappet and ignition settings are as standard. 

The S.U. carburettors are of the automatically expanding choke type, in which the size of the choke and the effective area of the jet vary according to the degree of throttle opening used against the prevailing load. This regulation of the choke size gives a fairly constant air velocity over the jet and ensures good atomisation, therefore multi-jets are unnecessary.  The single jet used is varied in effective area by a tapered needle which moves up and down in the jet orifice. The profile of the needle is decided to suit each type of engine and running conditions. Multi-carburettor installations cannot be successfully tuned unless the general condition of the engine. i.c., compression, ignition system. are in a satisfactory state. 

With regard to the carburettors themselves, the cleanliness of the section piston units, the position of needles, the jet centering and oil level in the dampers should be checked. The following sequence of tuning should be followed: 

  1. Remove the air cleaners and run the engine until the normal operating  temperature is reached. 

  2. Slacken one of the clamping bolts on the throttle spin idle connections (1) Fig. 11 so that the throttles may be set independently.

  3. Ensure that the throttle adjusting screws (2) Fig. 11 are holding the throttles slightly open, about one-and-a- half turns from being clear of the abutments. Disconnect the mixture control rod (1) Fig. 10. 

  4. The choke control screw (4) Fig. 11 should be clear of its abutment and the choke cable disconnected if it is likely to interfere with adjustment. 

  5. Set the engine idling speed to about 500 r.p.m. and using a length of rubber tube about 1 ft. long and 1 in. bore as a stethoscope, check the hiss of air at the carburettor intakes. They should be equal in volume, if not proceed as follows: 

  6. With a downward pressure on the throttle adjusting screw (2) Fig. 11 adjust each intake until the 'hiss' is equal and the speed is 500 r.p.m. To reduce 'hiss' unscrew the adjusting screw. 

  7. When the desired condition has been achieved, stop the engine and tighten the throttle spindle clamping screw and re-check. 

  8. Re-start the engine and allow it to idle at approximately 500 r.p.m.

     
  1. Check the mixture strength by lifting the piston off the front carburettor using the lifting pin (2) Fig. 10 approx. 1/32 in. (1,75mm) when:

    a.    If the engine speed increases the mixture strength of the front carburettor is too rich.

    b.    If the engine speed immediately decreases the mixture is too weak.

    c.    If the engine speed momentarily increases very slightly followed by a fall off in speed, the mixture strength is correct.

  2. Carry out a similar check on the rear carburettor, and if adjustments to mixture strength are necessary this can be varied by screwing or unscrewing the jet adjusting nuts (3) Fig. 10.  To enrich the mixture the nut should be screwed down, to weaken it screw the nut up.  During this adjustment it is necessary to ensure that the jets (4) are pressed upwards so that they are in contact with the adjusting nuts.  When the adjustments are satisfactorily completed the exhaust note should be regular and even.

  3.  Re-make any connections wich may have been disturbed and replace air filters.

 

Jet Centralising 

When the piston (5) Fig. 10 is lifted by hand, with the engine not running and the jet adjusting nut screwed up fully, it should fall freely and come into contact with the jet bridge with a soft metallic click. 

If this does not happen, then repeat the test with the jet in its fully lowered position. If the click is now audible and the piston falls freely then the jet nut must be re-centralised with the needle. 

The jet nut which is clamped in position by the gland nut (6) Fig. 10 is located in a clearance bore which permits a limited amount of float when the gland nut is slackened. Therefore, it can be moved until it is concentric with the jet needle, allowing the piston to fall freely to its lower position. To re-centralise proceed as follows: 

1.    Remove the air filters. 

2.    Remove the return springs (7) and pivot pins (8) (Fig. 10). Move the linkage out of the way. 

3.    Remove piston dampers (5) Fig. 11. 

4.    Withdraw the jet (4) Fig. 10 and remove the adjusting nut (3) and springs (9). 

Sabra Handbook Fuel System Pic 10
     
  1. Replace the adjusting nut and screw it up to its upperrmost position. 

  2. Slacken the gland nut and insert the jet. 

  3. Hold the jet in its upper position and move jet assembly laterally until the jet is concentric with the needle, then tighten the gland nut. When the correct condition is achieved, the piston assembly will fall freely, hitting the jet bridge with a soft metallic click. Replace the spring (g.), adjusting nut (3), jet (4), pivot pins, damper unit, etc. and replenish the dash pots (5) Fig. 11 with oil of S.A.E.20 viscosity. The oil level is correct when, using the damper as a dipstick, its threaded portion is approximately 1 in. above the dash pots when resistance is felt. The oil should be replenished, if necessary, every 3,000 miles. 

 Float Chamber Fuel Level 

The level of the fuel in the float chamber is governed 

 

by the action of the forked lever in the float chamber lid which acts upon the needle valve. The following procedure should be adopted if it is ever suspected that the fuel level is not correct. 

1.    Disconnect the fuel pipe and remove the float chamber lid securing bolt (3) Fig. 1 1. Lift off the lid. 

2.    With the lid inverted and the forked lever resting on the needle valve thus closing it, it should be possible to pass a 7/16 in. diameter (11->112 mm.) rod between the radius of the forked lever and the float chamber lid. If the forked lever fails to conform witbin 1/32 in. (0,7937 mm.) of the check figure, bend it carefully at the start of the fork section, but take care to keep both prongs parallel with each other. There should be no need to alter the fuel level unless flooding is experienced. This can be caused by grit jamming the needle valve, a punctured float or excessive engine vibration; these points should be checked first. 

3.    Re-assemble.

Sabra Handbook Fuel System Pic 11
     

K14 

SPECIFICATIONS AND REPAIR DATA

Fuel Tank Location... ... ... ...  ... ... ..... ... ... ... ... At rear of car, under luggage boot floor 

Capacity... ... ... ... ... ... ... ... . ... ... ...  81 Imp. galls. approx. (10,2 U.S. galls., 45,4 litres) 

Fuel Pump Type... ... ... ... ... . ... ... ..... ... .Diaphragm, operated by eccentric on camshaft 

Delivery Pressure... ... ... ... ... . ... ... ... 2 to 3-1/2 Ib/sq. in. (140,6 to 246,05 gm/sq. cm.) 

Inlet depression ... ... ... ... ..... . ... ... ... ... ... ... ... ... ... ......  ..10 in. (25,4 cm.) of mercury 

Fuel Pump Diaphragm spring: 

Test length... ... ... ... ... ... ...... . ... ... ... ... ... ... ... ... ... ... ... ... ... ...19/32 in. (15,081 min.) 

Test load .. ... ... ... ... ... ... .. ..... ... ... ... ... ... ... ... ..104 to 112 oz. (2,949 to 3,175 kg. m.) 

Rocker arm spring: 

Test length ... ... ... ... ... ... .. ..... ... ... ... ... ... ... ...... ... ... ... ... ... ... 23/32 in. (18,256 mm.) 

Test load  ... ... ... ... ... ... ......  ... ... ... ... ... ... ... ... ... ...164 to 172 oz. (4,65 to 4,88 kg. m.) 

 

Carburettor (Stage I) 

Type  ... ... ... ... ... ... ... ... .. .... ... ... ... ... ... ... ... ... ... ... Zenith, single-venturi downdraught 

Main jet ... ... ... ... ... ... ... .. ... ... ... ... ... ... ... ... ... ... ... ... ... ... .. . ... ... ... ... ... ...... ... ...  95 

Main air bleed ... ... ... ... ... .. .. ... ... ... ... ... ... ... ... ... ... ... ... ... ..   . ... ... ... ... ... ...  1,8 mm. 

Idling jet ... ... ... ... ... ... ... .. .. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...  45 

Compensating jet ... ... ... ... .. . ... ... ... ... ... ... ... ... ... ... ... ... ... ... . .. ... ... ... ... ... ... ... .105 

Accelerator pump jet ... ... .. ...... ... ... ... ... ... ... ... ... ... ... ... ... ... ...  ... ... ... ... ... ... ... ... 50 

Idling jet air bleed ... ... ... ...... .. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ..  . ... ... ... ... ... ... ... 70 

Choke tube diameter ... ... .. .... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...  28 mm. 

Needle valve ... ... ... ... ... .. ... ... ... ... ... ... ... ... ... ... ... ..... ... ... ... ... ... ... ... ... ... . 1,75 mm. 

Float chamber level: 

Float in ... ... ... ... ... ... ...... ... ... ... ... ... ... ... ... ... ... ... ... ..7/8 in. (22,5 mm.) below top face 

Float out ... ... ... ... ... .. ... ... ... ... ... ... ... ... ... ... ... ... ..1-5/16 in. (33,5 mm.) below top face 

 

Carburettor (Stage II) 

Type ... ... ... ..... ... ... ... ...  ... ... ...... ... ... ... ... ... ... ... ... ... .. ... ... ... ... ... ...  Twin 1/2 H4 S.U.

Main jet ... .. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...90 

Needle valve ... ... ... ... ... ... ... ... ... ... ... ... ...  ... ... ... ... ..G.S. Needle and red damper spring 

     

Common Technics