Carburettors are commonly found in internal combustion engines. Designed to mix fuel and air, they were the primary fuel-delivery method for car engines up until of the late 1980s. This vintage and classic car part has seen a demise due to the growing popularity of fuel injectors, but it still sees use as a cost-efficient alternative.
A valve located in the carburettor and usually connected via a cable to a control knob on the fascia, the choke is responsible for reducing the amount of air in the air-fuel mixture once the engine starts. Ensure the choke size is compatible with the make and model of your vehicle. Generally speaking, the two different types include fixed and variable size options. Fixed chokes remain steadfast in size; instead, the depression over the fuel jet hole is varied according to engine demand to ensure correct fuel flow. If too small, the car does not optimise its performance. Conversely, if too large, the fuel metering is negatively affected. Still, in the case of variable chokes, the size changes depending on the demand for fuel.
Whether shopping for a Weber carburettor or a Solex carburettor, for instance, take into account the number of barrels, or passageways, that it contains. One, two, and four barrel models are most common. For a smaller engine, consider purchasing a single-barrel carburettor; these units do not require as much power to operate and are proportionally sized. On the other hand, two-barrel carburettors prove most common and are ideal for engines with larger displacements, as they allow increased air to flow through. Still, four-barrel carburettors are reserved for high performance engines that require increased horsepower.
Side Draft vs. Downdraft Carburettors
Carburettors are often classified according to directional airflow. Side draft carburettors allow air to flow in horizontally; these units are renowned for their ease of installation in tight spaces. On the other hand, downdraft carburettors are set on top of the engine.
OEM vs. Aftermarket
OEM carburettors come highly recommended. Constructed by the original equipment manufacturer, they offer a precise fit with other OEM car parts. On the other hand, aftermarket parts, while not often as reliable, are renowned for their affordability. When purchasing the later, ensure the part is of high quality for optimal safety and performance.
Catalytic carburettors contain a catalytic metal, often platinum or nickel, to break down the fuel so that it mixes more evenly. The presence of metal also allows the carburettor to break down engine exhaust, helping to improve air quality.