Carburettor

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

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

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 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

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

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

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

The fixed-jet carburettor resembles the simpler variable-jet type (See How variable-jet carburettors work ) in having a venturi - a constricted neck - through which air flows on its way to the engine . Read more