Service Guide

How to keep your Cambridge shipshape and Bristol fashion

How to keep your Austin A40, A50 or A55 MKI in fine fettle.

Model evolution

The A40 and A50 Cambridge launched in late 1954 represented a significant step forward from its Somerset predecessor. It introduced unitary construction and BMC’S then-new B-series engine, available in 1200cc and 1489cc displacements. This drove a live axle at the rear via a four-speed column-change gearbox. The A50 was fitted with 13in rather than 15in wheels from October 1956 and gained higher compression and final drive ratios.

The mildly-restyled A55 replaced the A50 in January 1957, but remained mechanically very similar. The 1489cc models were offered with a semi-automatic ‘Manumatic’ transmission or a Borg-warner overdrive. Very late A55s received a floor-change. Saloons, vans and pick-ups were built, the latter remaining in production until 1973.

What’s it like to work on?

With a generous engine compartment and a traditional leaf-sprung rear-wheel drive layout, the Cambridge is straightforward in every respect. Under-bonnet access is good, with the exception of the oil filter housing, which is partially obstructed by the battery from above and by the suspension subframe from below. The overhead valve B-series engine is very easy to maintain, with valve clearances set by conventional screw and locknut adjusters. The car has a multitude of grease-points, which should attended to sparingly but regularly – ideally every 1000 miles.

Parts and support

Cambridge-specific parts are still available at reasonable prices from a number of suppliers, including NTG Motor Services (bmcfarina.com) and Longbridge Motor Spares Ltd (longbridgemotorspares.co.uk). A lot of service items are shared with other models and are very widely available.

Clubs and support

Enthusiastic help and know-how comes from the Cambridge-oxford Owners Club (co-oc.org) and Austin Cambridge Westminster Car Club (acwcc.org).

This applies to…

The mechanical set-up of the later 1.5-litre Farina Cambridges is generally similar. The engines are almost identical.

Propshaft You will need Hinges and catches Tyres Trolley jack, axle stands, oil pan, AF spanners, feeler gauges, long lever, test lamp or multimeter, grease gun, oil can. Attempt to rock the two sections of each universal joint in opposite directions to check for play. Lubricate all hinges and catches with engine oil or aerosol grease. Wipe off excess. Check for wear and damage. Investigate uneven wear. Tyre pressures (crossplies): 15in – 24psi; 13in – 26psi. Add a few psi for radials.

Timing marks are located on the timing cover and crank pulley, viewed from under the car. Fine adjustment can be made using the vernier on the distributor. Release the 7/16in AF distributor clamp bolt and rotate the body to make larger adjustments. Inspect the distributor cap, rotor arm and HT leads. Clean and gap the points every 3000 miles; replace every 6000. Apply drops of engine oil to the mechanical advance mechanism, points pivot and felt pad (if fitted). Put a tiny dab of grease on the cam. Apply a few drops of engine oil to the rear bearing. Gap the electrodes and clean with a brass wire brush every 6000 miles. Replace every 12,000. Put a dab of copper grease on the threads. Inspect the radiator, pressure cap, hoses and heater for deterioration and leaks. Check for play in the water pump pulley. Lubricate with water pump grease if a greasepoint is provided. Flush the system, test the thermostat and refill with fresh antifreeze mix every two years. Remove the rocker cover (two ⅝in AF bolts). Replace the gasket if it’s ailing. Rotate the engine using the starting handle and use the ‘rule of nine’ to set the valve clearances: set valve 1 with 8 fully open, 2 with 7 fully open, etc. Remove the filter and clean its gauze in paraffin. Dry before refitting. Spark plugs Engine oil Remove the ¾in AF sump plug and drain the oil with the engine warm. Replace the copper washer, if necessary. Undo the filter housing bolt and remove it downwards. Beware of spillage. Clean the housing and fit a new filter element. Lightly oil and fit a new rubber seal. Fill the bowl with fresh oil and refit. Ignition timing Fanbelt Check the belt’s condition and tension. Deflection under firm thumb pressure halfway between the dynamo and crank pulley should be around ¾in (20mm). Pivot the dynamo to adjust. Ignition system Dynamo Valve clearances Cooling system Air filter

Carburettor Lubricate the throttle and choke linkages and ensure that both open fully. Make sure the accelerator pump emits a healthy jet of fuel when the throttle is opened. Rotate the idle mixture screw in a few turns, then out until you find the ‘sweet spot’ where the engine runs fastest and smoothest. Adjust the idle speed afterwards, if necessary.