Most new cars are fitted with an automatic choke rather than a manual one. The choke automatically opens and closes the choke butterfly (or valve) in the carburettor depending on the temperature of the engine. It may be plumbed directly into the cooling system, or linked electrically to the engine temperature sensor.
In practice, an automatic choke has several disadvantages. First, the driver has no control over it, unlike a manual choke. Second, it often goes wrong. It may fail to operate at all, making the car difficult or impossible to start.
The opposite may also happen and the choke fails to cut out, either partially or totally. This wastes fuel and the engine fails to run properly because the mixture is too rich - it may also run-on or clog up with oil.
For these reasons many drivers prefer a manual choke. If your car has an automatic choke and is giving trouble, you can usually convert it to a manual one with a special conversion kit.
Fitting a choke conversion kit
There are a great many kits on the market, each designed to work with a particular carburettor. They all work in much the same way. A choke control fits to the dashboard. A cable runs from the control through the engine bay bulkhead and links up to the carburettor. Some kits come with a warning light to remind you the choke is out.
Buying the kit
You need to check, with either your car dealer or the accessory shop, whether a conversion kit is available for your carburettor - not all types are catered for.
Make sure you know what make and model of carburettor your car is fitted with so that you can buy the right kit. Check carefully because some models are fitted with one of several carburettors - look for identification marks on the side.