The Austin Healey 3000 is one of Britain's most celebrated sports cars — a big-hearted, torquey machine with a character all of its own. When this pair of HD8 SU carburettors arrived at our workshop, they told the story familiar to any classic car that's covered serious miles: corroded flanges, worn spindles, tired internals, and years of grime that no ordinary cleaning was going to shift.
Here's the full story of how we brought them back.
Both carbs as received — corroded flanges, dirty bodies, worn condition]
The pair as received — corroded flanges, grimy bodies, and worn internals after a long life on a 3000.
The Condition on Arrival
Both carbs came off the same Healey and had clearly worked hard together. A closer look told us everything we needed to know: the spindle bores were worn, the throttle plates loose on their shafts, and the alloy bodies were carrying the kind of dirt that soaks in over decades. The float chambers and jet housings had surface corrosion throughout.
Single carb close-up before rebuild — worn and corroded condition]
A closer look at one of the carbs before work began. Note the corrosion on the flange face and the general deterioration of the body.
No amount of new jets or needle tweaking will fix a carburettor with worn spindle bores — this pair needed a proper overhaul, not a parts swap.
Strip Down
Every rebuild starts with a full strip to bare components. Both carburettors came apart completely — suction chambers, dashpots, slides, needles, jets, float chambers, spindles, linkages, every last screw and washer. Each part is assessed individually: what can be cleaned and reused, what needs replacing.
Carb partially stripped on workshop floor — spring and suction dome removed]
Early in the strip-down — the suction dome and main spring off, giving access to the slide and body internals.
Once stripped, everything goes through our ultrasonic cleaner. The ultrasonic process gets into galleries, drillings, and recesses that a solvent bath or brush simply can't reach — essential on carburettors that have accumulated years of fuel varnish and oxidation. After cleaning, a hand polish brings the alloy and steel up.
Full teardown — all components of one carburettor laid out on workbench]
Full teardown of one carburettor. Every component comes apart and is assessed individually before cleaning and reassembly.
Spindle Bearing Overhaul
This is what separates a proper rebuild from a parts refresh. Worn spindle bores — where the throttle spindle runs through the carburettor body — cause air to bypass the throttle disc, making accurate mixture control and carburettor balancing virtually impossible. You can't tune around a worn spindle bore; it has to be fixed at the source.
We ream the carburettor bodies to accept new phosphor bronze bearings, pressed and fitted using specialist tooling on the drill/milling machine. The spindle runs through both new bearings with zero play. Done correctly, it's a permanent solution — not a patch-over.
All-New Internals Throughout
With the bodies sorted, we fitted a complete set of new parts:
- Gaskets — full set, fresh throughout
- Diaphragms & springs — new flexible diaphragms and correct-rate springs
- Float needles — new needles and seats for accurate fuel metering
- Slide needles — replacement needles for correct mixture delivery
- Damper springs — new springs for correct dashpot action
- Upgraded spindle seals — uprated seals to complement the new bearings
- Damper oil — correct SAE 20 SU damper oil
The core of the parts used in this rebuild comes from our HD8 Major Repair Kit (MRK2218) — a comprehensive kit covering all the service items for HD8 carburettors.
The Finished Article
Both carburettors rebuilt, polished, and ready to go back on the Healey.
Rebuilt pair from front — polished suction chambers, side by side]
Front view of the rebuilt pair. The polished suction chambers and clean bodies are a far cry from where they started.
Rebuilt pair from rear/top — showing damper caps and jet linkage detail]
Rear view showing the jet linkage, mixture screws, and damper plugs — everything refitted, clean, and correctly set.
The owner gets back two carburettors that will behave identically — essential for a twin-carb setup where balance between the two is everything. Sharp throttle response, a stable idle, and accurate mixture delivery that actually responds to adjustment.
Thinking About a Rebuild?
If your SU carburettors are hunting at idle, running rich, or have simply never been properly overhauled, we rebuild individual carbs and matched pairs to the same standard as these — full strip, ultrasonic clean, spindle bearing overhaul where required, and all-new internals throughout.
Find out more about our SU carburettor refurbishment service →
If you're rebuilding your own carbs, our Major Repair Kits has everything you need.