Weber Carburettors

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The most humble E30, the 316 was fitted with a carburettor fuel systems rather than an injected engine. It came fitted with a Pierburg 2BE carburettor.

While beautiful in its intricacy, the Pierburg unit does not age well, and more and more owners look for a superior carb to fit as a replacement, the most popular of which are the Weber Carburettors.

NB: While the Weber offers undoubtedly superior performance to the original Pierburg unit, you will lose the use of your econometer gauge.

WeberDTML.jpg

Models

Weber makes carburettors for a wide range of vehicles, and not all can be slapped onto the M10 engine. Each Weber unit is described by two pieces data; the Choke Size, and the model number. The most commonly fitted size of Weber is the 32-34 DTML.

The following fitting guide applies to the 32-34 DTML version.

Removal

Disconnect the battery first!

Air Filter

Disconnect the small vacuum pipe leading to the air filter temperature switch from the connection to the inlet manifold.

Disconnect the engine breather pipe from the underside of the air filter

Disconnect the air by-pass pipe from the underside of the air filter adjacent to the temperature switch

Loosen the air filter intake support bracket nut

Remove the air filter top cover by removing the centre screw and release the securing clips

Disconnect the hot and cold air intake ducting hoses

Remove the air filter retaining ring by undoing the three securing nuts Lift clear the complete air filter assembly.

Electrical

Remove the carburettor control solenoid, located beneath a plastic dust cover on the inner wing. Refit the dust cover. Disconnect all electrical feed wires from the carburettor. Remove the wiring loom retaining clamp located on the carburettor body next to the cam cover. Disconnect the electric supply to the distributor vacuum solenoid valve located on the bulkhead. Secure all of the above electrical connections in a suitable position using four of the provided cable ties, as they are no longer live or required.

Distributor Vacuum Advance Disconnect

Disconnect from the carburettor the small black rubber pope leading to the solenoid valve located on the bulkhead. Disconnect the rubber vacuum pope leading from the solenoid valve at the connection of the distributor diaphragm. Remove the solenoid valve and pipework as they are no longer required.

Vacuum Pipe Disconnect

Disconnect from the carburettor idle control unit the black rubber vacuum pipe which leads through the bulkhead. This pope will not be used in the new installation and must be secured out of the way using the remaining cable tie. N.B. The fuel consumption gauge fitted to this vehicle will not function without the electronic and vacuum inputs which are not fitted to this conversion. Disconnect from the air by-pass valve the black rubber vacuum pope leading to the carburettor. N.B. This By-pass valve will not be active in the new installation and must not be connected to any vacuum source on either the carburettor or manifold. Automatic transmission models only - disconnect the two small vacuum pipes leading from the carburettor at the connection to the thermo switch on the engine thermostat water housing. N.B. The thermo-switch connections will not be used in the new installation.

Accelerator Cable Disconnect

Disconnect the inner cable from the throttle lever by removing the plastic connector. Disconnect the adjustable outer cable from the anchor bracket on the carburettor.

Automatic Gearbox Kick Down Cable Disconnect

Automatic transmission models only

Disconnect inner kick down cable from the lever on the carburettor by unhooking. Disconnect the adjustable outer kick down cable from the anchor bracket on the carburettor.

Fuel Line Disconnect

Disconnect from the fuel pump outlet the fuel supply line leading to the carburettor

Carburettor Removal

Remover the four securing bolts located within the carburettor top flange, then lift clear the complete carburettor assembly. Inspect the carburettor rubber mounting block for deterioration to the sealing face and splitting of the side walls (replace where necessary).

Fitting

Carburettor Adaptor Fitting

Fit the new accelerator cable anchor bracket supplied to mounting point A on the underside of the new base adaptor using the two new screws, plain washers and Nyloc nuts provided, located in the two fixing holes furthest from the anchor bracket edge, as shown in the illustration. Automatic transmission models only - Fit the kick down cable anchor bracket provided, below the accelerator cable anchor bracket at point A on the underside of the base adaptor and secure as detailed above.

Place the new carburettor base adaptor onto the manifold mounting block, with the cast arm towards the engine cam cover, secure in position using the four Allen screws provided.

Fit the four new carburettor mounting studs provided into the base adaptor, using two carburettor securing nuts locked together.

Place the new carburettor flange gasket provided onto the base adaptor.

Fit the new Weber carburettor onto the base adaptor with the fuel line inlet pipe towards the front of the vehicle, as indicated by arrow X on the illustration. Secure the carburettor in position with the four nuts, plain washers and lockwashers provided.

Accelerator Cable

Fit the new throttle return spring provided, between the throttle lever C on the carburettor and the anchor point D on the base adaptor.

Cut the original end ferrule from the accelerator inner cable, and remove the sliding nipple and plastic connector.

Insert the accelerator outer cable into the mounting bracket and set to approximately the centre of adjustment.

Fit the new adjustable ferrule clamp to the throttle lever C on the carburettor, then insert the accelerator inner cable and secure.

Adjust the accelerator outer cable adjuster so that a small amount of free play exists in the throttle closed position. Fully open the throttle by depressing the accelerator pedal, then adjust the pedal stop beneath the pedal to prevent the linkage being over stressed. Check that the throttle returns correctly to the idle position, and a small amount of play exists in the cable.

IMPORTANT: Check the throttle operation before starting or road testing the vehicle.

Automatic Gearbox Kick Down Cable

Connect the inner kick down cable to lever E on the carburettor. Connect the outer kick down cable to the anchor bracket, then refit the adjuster nut. Where necessary, adjust the cable so that the gearbox changes down just before full throttle position.

IMPORTANT: Check the throttle operation before starting or road testing the vehicle.

Fuel Line Connection

Fit the new fuel line provided, between the fuel pump outlet and the inlet pipe B on the carburettor. Secure the pope connections with the two hose clips provided.

Distributor Vacuum Advance Pipe

Connect the new vacuum advance pipe supplied to the distributor vacuum diaphragm and to tube F on the carburettor.

Choke Cable

Remove the fascia under panel from the steering column. Fit the new choke cable supplied in a suitable position to the left of the steering column either directly into the fascia panel using the two mounting plates, or alternatively mount the cable utilizing the bracket and screws provided. To secure the choke cable in position where the rear adjust nut is inaccessible, first remove the inner cable and black outer bezel, adjust the rear nut so as to allow approximately 4mm of thread to protrude from the mounting face, then refit the black bezel and secure using a 6mm Allen key. Refit the inner cable.

Route the choke cable carefully behind the fascia and pass through the engine compartment speedo cable grommet. Following the route of the accelerator cable, align the choke cable to the anchor point G on the carburettor, then pull out the choke cable knob approximately 6" and cut through the cable at this point. Push in the choke cable knob and secure the outer cable to the anchor point G and the inner cable to the actuating lever H on the carburettor.

Air Filter Adapter

Place the new mounting plate and gasket supplied onto the carburettor top face. Fit the air filter assembly into position, on the mounting plate and support bracket. Secure the air filter with the clamping ring, four screws and lockwashers provided. Then secure the air filter intake support bracket nut. Reconnect the engine breather pipe to the underside of the air filter. Reconnect the small vacuum pipe leading from the air filter to the air connection on the inlet manifold. Reconnect the air bypass hose to the underside of the air filter. Reconnect the hot and cold air ducting hoses to the air filter intake. Refit the air filter and cover using the original retaining clips and the central screw.

Starting Procedure

Reconnect the battery earth terminal.

Pull the choke knob fully out, turn the key to crank and start the engine, then push in the choke knob to maintain approximated 1200RPM until normal working temperature is attained, and the choke can be fully returned.

Set the engine idle speed to approximately 900RPM by adjusting the idle stop screw J.

Adjust the idle mixture screw K to obtain the highest engine speed.

Repeat the last two operations so that the highest attainable engine speed by adjusting the mixture screw K is 900RPM.

The final adjustment should be made by turning the mixture screw approximately a half turn clockwise to weaken the mixture and so obtain the emission value of CO 0.5-1.0% Vol. The engine idle speed should now stabilise at 850RPM.

IMPORTANT: In order to achieve the maximum benefit from your new Weber carburettor, we advise that the condition of the engine be checked. Also a routine engine tune is recommended, all setting to the manufacturer's specifications, and replace service items where necessary. Where varying engine conditions exist some individual calibration adjustments may be necessary.

Calibration

Primary Part No. Secondary Part No.
Main Jet 117 73405117 125 73405125
Air Corrector 175 77501175 200 77501200
Emulsion Tube F22 61450222 F25 81450225
Idle Jet 55 74403055 80 74400060
Pump Jet 45 76417045
Needle Valve 175 79531175
Float level (with gasket) 8.0mm +/- 0.25