The Jaguar XJ6 Series 1, built between 1968 and 1973, is regarded by many as the pinnacle of classic British luxury and engineering. With its graceful lines, sublime ride comfort and powerful straight-six engine, this model was a direct attack on the established order in the luxury segment. What makes this car truly special under the bonnet is the use of SU HS8 carburettors combined with an AED, a system every bit as intriguing as the character of the car itself.
The engine and the carburettors: SU HS8
The XJ6 Series 1 was available with both a 2.8-litre and a 4.2-litre straight-six engine, both from the legendary XK engine family. The 4.2-litre version used two SU HS8 carburettors, an impressive configuration with a 2 inch (50.8 mm) bore per carburettor.
These HS8s are typically British: simple in principle, brilliant in execution. They work with a variable venturi and a piston needle, giving precise fuel metering whatever the engine speed or load. Properly set up they are quiet, smooth and surprisingly efficient.
The starting problem: the AED
Where the SU HS8s earn glowing reviews, the AED (Automatic Enrichment Device) is another story. This automatic choke system was meant to simplify cold starting. In theory the driver only had to turn the key and the AED would provide the right enrichment until the engine was up to temperature.
In practice the AED is a notorious source of trouble:
- Running too rich with a warm engine
- Poor idling
- Unpredictable engagement
The system is fully automatic and has no manual override, which makes setting up or testing harder. The result: many Jaguar owners have replaced the AED over the years with a manual choke or a dual start-knob configuration.
Overhaul or modification?
At Carburateur Service Nederland · your carburettor specialists in the Netherlands · we regularly receive SU HS8s with AED from Jaguar XJ6 owners. We can overhaul these carburettors completely, including:
- Float needles and seats
- Damper oil and piston checks
- New gaskets and diaphragms
- Synchronisation on the test bench
And the AED? We can overhaul it, disable it or remove it completely, in consultation with you. In many cases we recommend a conversion to a manual choke: it improves reliability and you keep the original look.
Final thoughts
The Jaguar XJ6 Series 1 with SU HS8 and AED is a beautiful classic with an eye for detail. Its charm lies in the combination of luxury, engineering and character. Have the carburettors properly overhauled and know how to handle the AED (or choose the right alternative), and you will find this Brit still holds its own, on the road and in the garage.
Want to know more about overhauling SU HS8 carburettors or converting the AED? Feel free to get in touch. We are happy to help you weigh it up, from classic original to reliably modified.