HS4 Triple Carburettors for Austin Healey 3000 Mk II
This HS4 Triple Carburettor Set is built for Austin Healey 3000 Mk II BN7 and BT7 tri-carb models produced from late May 1961 to March 1962 (BN7) and June 1962 (BT7). While some owners choose to fit these to earlier Mk I cars as a performance modification, this configuration was only part of the factory specification for the Mk II tri-carb models.
The set includes three brand-new SU HS4 carburettors, correctly spaced, mounted, and linked for installation onto the factory-type triple-port inlet manifold. Built to SU specification, the units are pre-assembled for ease of fitting, with final tuning recommended once installed.
Benefits
- Correct triple-carburettor configuration for Mk II BN7 & BT7 tri-carb models
- Supplied pre-assembled with correct spacers and linkages
- Balances fuel delivery across all cylinders for smoother performance
- Brand-new SU HS4 components for long-term reliability
- Suitable for factory-correct restoration or performance applications
- Compatibility & Fitment Guidance
Factory-correct for Austin Healey 3000 Mk II BN7 (late May 1961 – March 1962) and BT7 (late May 1961 – June 1962) with the original-style triple-port inlet manifold. Can be fitted to earlier Mk I or later Mk II/BJ7/BJ8 cars only with the appropriate manifold conversion. Always confirm manifold type and linkage compatibility before ordering.
Why Fit This Assembly
The triple-HS4 setup provides the distinctive throttle response and induction character of the original Mk II tri-carb cars. New units eliminate issues common with worn carburettors, such as uneven fuelling, spindle wear, and linkage play.
Technical Notes
- SU Type: HS4 (1½″ bore)
- Manifold Spacing: As per factory Mk II triple-port inlet manifold
- Contents: 3× brand-new HS4 carburettors, interconnecting linkages, and correct spacers
- Installation: Bench-assembled and pre-aligned; final tuning required after fitting
Servicing & Maintenance
Service kits are available for individual HS4 units (front & centre, and rear). Regular inspection of linkages, spindles, and seals is recommended for sustained performance.
Factory Carburettor Reference
Use the table below to confirm the original factory carburettor type for your Austin Healey 3000 variant.
Factory Carburettor Reference
| Model | Chassis Codes | Production Dates | Factory Carbs | Bore Size |
| MK I (3000) | BN7/BT7 | Mar 1959 - May 1961 | Twin SU | HD6 1¾″ |
| MK II (3000) - Tri-carb | BN7/BT7 | Late May 1961 - Mar 1962 (BN7)
Jun 1962 (BT7) | Triple SU | HS4 1½″ |
| MK II (3000) - BJ7 | BJ7 | Aug 1962 - Oct 1963 | Twin SU | HS6 1¾″ |
| MK II (3000) | BJ8 | Oct 1963 - 1967 | Twin SU | HD8 2″ |
FAQ
Will this fit my 3000 MK1 (BN7 or BT7)?
Not as a direct factory-correct replacement — the triple-HS4 was factory spec only on Mk II BN7/BT7 tri-carb models. It can be fitted to Mk I cars only with the correct triple-port manifold and linkage.
Is this the same setup originally fitted at the factory?
Yes — if you own a Mk II BN7/BT7 tri-carb from late May 1961 to mid-1962. For all other models it would be a performance modification. Yes — if you own a Mk II BN7/BT7 tri-carb from late May 1961 to mid-1962. For all other models it would be a performance modification.
Do I need to modify anything to fit this?
If your car already has a factory-type triple-port HS4 manifold and linkage, no modification is needed. Twin-carb manifolds or non-standard setups will require conversion.
What else do I need to complete installation?
You’ll need the correct triple-port inlet manifold, throttle cable or linkage, and suitable gaskets and air filters.
Are these carburettors reconditioned?
No — these are brand-new HS4 units built to SU specification.