Carburettor Components & Rebuild

Carburettor Components, Jets & Rebuild Kits

The carburettor is a precision instrument — a collection of carefully calibrated circuits, drillings, and components that work together to deliver the correct fuel mixture across the entire operating range of the engine. Understanding how each component affects carburettor behaviour is the key to optimising performance and driveability from a carburetted engine, and having access to quality individual components makes the job of building, rebuilding, and fine-tuning a carburettor accessible to any competent builder.

With 245 individual carburettor components from Holley, Quick Fuel, and Demon, our components range is one of the most comprehensive available — covering jets, power valves, accelerator pumps, floats, choke assemblies, and rebuild kits for the most popular American performance carburettors.

Metering Jets — The Primary Tuning Tool

Jet selection is the most common and accessible tuning adjustment on a four-barrel carburettor. Main jets meter fuel flow through the primary and secondary circuits across the mid to upper throttle range. Going up in jet size richens the mixture; going down leans it. The correct jet size depends on altitude, air temperature, engine tune, and application — what works perfectly at sea level in cold weather will be too rich at altitude in summer. Our comprehensive jet range covers every standard and non-standard size in increments that allow precise calibration.

Power Valves — Enrichment at Wide Open Throttle

The power valve opens under wide-open-throttle conditions to provide additional fuel enrichment for maximum power. Power valve selection is based on the manifold vacuum reading at idle — the valve should open slightly below idle vacuum to ensure it doesn't contribute to part-throttle fuel delivery. A blown power valve — damaged by engine backfire — is a common cause of carburettor running problems and rich conditions at idle. Replacement power valves in our range cover the full range of opening points.

Accelerator Pumps — Throttle Response and Tip-In

The accelerator pump squirts raw fuel into the venturis during rapid throttle opening to prevent the lean spike that would otherwise occur as air velocity increases before the main circuits catch up. Correct accelerator pump sizing eliminates the flat spot or stumble on tip-in that characterises a poorly set up carburettor. Our pump range includes standard and high-capacity diaphragms, pump cams in multiple profiles to adjust the rate and duration of fuel delivery, and complete accelerator pump assemblies for full replacement.

Floats, Needles, Seats, and Rebuild Kits

A complete carburettor rebuild with quality components is often more cost-effective than chasing drivability problems through individual component replacement. Our rebuild kit range covers the major Holley and compatible carburettor families and includes all the seals, gaskets, power valve, accelerator pump, and needle-and-seat assemblies required for a complete overhaul. Quality floats — whether nitrophyl or brass — maintain correct fuel level consistently and are one of the highest-impact components in carburettor performance and fuel delivery accuracy.