Three levels of carburettor kit are available, allowing the scope of overhaul to be matched to the carburettor's condition and the owner's budget. Choosing the right level depends on an honest assessment of the carburettor's wear, the most common mistake is fitting a service kit to carburettors that actually need a full rebuild, resulting in new internal components fitted to worn housings that cannot maintain the correct air and fuel metering.
Full Rebuild Kit
A full rebuild kit includes everything in the service kit plus throttle spindles, spindle bushes, throttle discs, and disc screws for both carburettors. This is the correct choice when the throttle spindles have significant play, tested by gripping the spindle end and attempting to rock it in the carburettor body. Any perceptible movement indicates worn bushes, which allow air to be drawn in around the spindle, weakening the mixture and making the idle speed impossible to set correctly. Worn spindles also prevent the carburettor from ever sealing properly at the throttle disc, causing an air leak that no amount of jet adjustment can compensate for.
The rebuild kit restores the carburettor to as-new condition and is the recommended choice for any carburettor that has not been overhauled within the last 30,000 miles or where the spindle play test reveals any movement.
Service Kit
A service kit includes the gasket kit contents plus float chamber needles and seats, jet assemblies, and clips for both carburettors. This level of kit is appropriate when the throttle spindles are still tight but the fuel metering components, needles, jets, and float chamber hardware, have worn or deteriorated. The float chamber needle and seat are the components most commonly responsible for flooding, as the needle tip wears and can no longer seal against the seat to shut off fuel flow when the float chamber reaches the correct level. A service kit restores the fuel metering to factory specification without the expense of the spindle and bush components.
Gasket Kit and Sundries Kit
A gasket kit covers the manifold gasket, air filter gasket, suction chamber damper washer, float lid gasket, and jet union washer and seal for a single carburettor, two kits required per car. This is a basic maintenance kit for carburettors that are in good mechanical condition but have developed minor leaks or seepage. A sundries kit contains the small hardware frequently lost during dismantling: choke cam pivot bolt and tubes, suction chamber screws, float lid screws and washers, stop screws and springs, jet nut, jet spring and washer, spindle lock tab, and float pivot pin, all for a single carburettor. Having a sundries kit to hand before starting any carburettor strip-down avoids the frustration of discovering missing or damaged hardware during reassembly.
Tuning Tools and Carburettor Cleaner
An SU tuning tool kit provides the specialist tools needed for correct carburettor setup, including the jet adjusting spanner that is essential for mixture adjustment on the HS6 carburettor, attempting jet adjustment with a standard spanner risks damaging the soft brass jet adjusting nut. SU carburettor cleaner aerosol removes gum deposits, varnish, and fuel residue from carburettor bodies, suction chambers, and jets during servicing. These deposits build up over time, particularly if the car has stood unused with fuel in the float chambers, and restrict the movement of the piston, needle, and jet, causing poor throttle response and erratic mixture that cannot be corrected until the deposits are removed.