A fixed-jet carburettor mixes air and fuel by means of several jets . The jets are small holes which allow precisely controlled amounts of fuel or air to flow through them. The amounts are governed by the diameter, length and shape of the jets. Read more
Anti-pollution laws in many countries now limit the volume of poisonous carbon monoxide gas (CO) which may be emitted from a car exhaust. Read more
The fuel supply system is generally reliable and any problems that do occur are usually traceable to the pump , the fuel filter or the tank. Occasionally, however, the fault lies in the fuel line between the tank and the engine . Read more
A blocked fuel-pump filter will cause the engine to cut out intermittently, particularly at high speeds, and it may stop altogether. Read more
If a car stops and has not run out of petrol, check whether there is petrol in the carburettor . If there is not, there is a fault in the fuel system . Read more
The Stromberg carburettor does not have a regular service schedule, but should be cleaned about once a year. Replace worn parts as necessary. Read more
Over a period of time, dirt inevitably gets through the fuel filter of a carburettor , and chemicals in petrol leave residues which can eventually clog parts of it. Read more
The Varajet carburettor used on many Vauxhalls and Opels is a hybrid between fixed-jet and variable-jet (for example, SU) types. It is as sensitive to dirt and sediment as any fixed-jet carburettor, and needs careful cleaning about once a year. Read more
The Ford Variable Venturi carburettor is fitted to many small Fords. Read more
If the fuel gauge reads empty when you know there is fuel in the tank, the cause may be a faulty sender unit the electrical device that measures the level. Read more
Remove the top of the pump first. It is held on by a central bolt or screw, except on the SU AUF 700, which is held by three screws that also partly hold the halves of the body together. Read more
The SU carburettor is simple to strip. It has only one jet (except in a few special types) and very few moving parts. It is very reliable, but it can become dirty and choked — and some parts wear out. Read more
Fixed-jet carburettors are easily blocked by small dirt particles and chemical residues from fuel , because some of the jets are very small. Dismantle and clean them about once a year. Read more
Any fuel leak, however small, can cause a fire. Do not drive a car with a suspected leak until you have cured it. Never leave a car dripping petrol where a passer-by may throw a cigarette end under it. A small fire extinguisher, fitted where you can get at it quickly, is a valuable accessory. Read more
The carburettor is often suspected of causing an engine to run roughly, when the real source of the trouble may be something quite different. Read more
Unlike other types of carburettor , which have fixed jets , the SU has only one jet, so the mixture setting affects the engine throughout its speed range. Read more
The Stromberg CD carburettor , like the SU (See Adjusting an SU carburettor ), is a constant-depression carburettor, hence the CD. Read more