The fuel system upgrades section covers aftermarket and improved-specification components for both the air intake and fuel delivery sides of the system, suiting fast-road, sprint, hillclimb, or competition use as well as engine bay cosmetic enhancement on restored cars.
Performance Air Filters
High-flow air filters are available in several configurations. Replacement high-flow filter elements that fit within the original housings provide a discreet improvement in airflow without altering the external appearance, suitable for cars where the original air cleaner look should be retained. Individual pancake-style filters mount directly to the carburettor intakes, replacing the original housings entirely and providing substantially increased airflow. Stub stacks, open trumpet intakes without any filtration, are available for competition use only, as they offer maximum airflow at the expense of engine protection from dust and debris.
Carburettor Tuning After Filter Changes
When fitting any performance air filter, a carburettor needle change is strongly recommended to maintain the correct fuel-air ratio, increased airflow without a corresponding increase in fuel will lean the mixture, causing detonation, overheating, and accelerated valve and piston wear. Needle recommendations for common filter and exhaust combinations are detailed in the Carburettors section. For the 1275cc, the needle type also depends on whether the carburettor uses a fixed needle or a biased needle. For the 1500, all needles are of the biased type.
Carburettor Dashpot Covers
Polished alloy and chrome dashpot covers replace the standard pressed steel SU carburettor suction chamber covers, giving the engine bay a cleaner, more finished appearance. They are a direct replacement requiring no modification to the carburettor, and are available for both the HS2 (1275cc) and HS4 (1500cc) SU carburettors. The covers must be matched to the carburettor type, as the HS2 and HS4 have different suction chamber diameters.
Polished and Stainless Heatshields
The carburettor heatshield fitted between the exhaust manifold and the carburettor body prevents radiant heat from the exhaust manifold affecting fuel mixture, carburettor operation, and inlet air temperature, particularly important for slow-moving cars in summer traffic where vapour lock would otherwise occur. Polished alloy and stainless steel replacement heatshields offer the same functional protection as the original mild steel item, with improved corrosion resistance and a smarter engine bay appearance. Stainless heatshields are available for both the 1275cc and 1500cc applications, matched to the differing manifold and carburettor mounting arrangements of each engine.
Performance Fuel Pumps
Performance fuel pumps with higher flow rates are available for engines producing significantly more power than standard, ensuring fuel supply keeps pace with the engine's increased demand at higher rpm. Pumps are typically of solid-state design for reliable operation at sustained high speeds.
The standard SU pump is generally adequate for fast-road tuned engines, but Stage II builds, supercharger conversions, or any forced-induction installation will benefit from an uprated pump.
Fuel Regulators and Braided Hose
Fuel regulators allow precise control of fuel pressure to the carburettors, which is particularly useful when an uprated pump has been fitted and the standard SU float valves cannot accommodate the higher pressure. A regulator set to deliver between 2 and 4 psi to the carburettors avoids float valve flooding while maintaining adequate supply during full-throttle operation. Stainless steel braided fuel hose offers improved durability, heat resistance, and abrasion resistance compared to standard rubber hose, with a smarter appearance suited to engine bay rebuilds.
Fuel Cut-Off Kit
A fuel cut-off kit provides a cockpit-mounted valve to shut off the fuel supply in an emergency, a sensible safety addition for any car used in competition, where rule books often mandate such a system, and a worthwhile addition for any car used regularly given the consequences of a fuel leak in an accident. The kit includes the cut-off valve, mounting hardware, and the necessary hose and clip components.