Three S.U. Carburetors and Intake Manifolds for Jaguar590
triple SU HD8 (2-inch) setup is the performance benchmark for the Jaguar XK engine (3.8L or 4.2L). While standard on the Series 1 E-Type and the Mark X (420G), it is a highly prized upgrade for Series 2 E-Type owners looking to replace the restrictive twin Zenith-Stromberg units.
1. The Critical Difference: E-Type vs. Mark X
If you are sourcing a used setup, you must verify which manifold you are buying. They look nearly identical but are not interchangeable without modification.
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E-Type Manifold: The intake runners are cast with a downward slope. This lowers the carburetors by about an inch to clear the E-Type’s low-profile bonnet.
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Mark X / 420G Manifold: These runners are either straight or slope slightly upward. If you install a Mark X setup on an E-Type, the “dashpots” (the tall bells on top of the carbs) will hit the underside of the hood.
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The “Hisser”: Mark X setups originally used an electric auxiliary starting carburetor (the “hisser”) located between the front and center carb. E-Type units use a simpler manual choke.
2. Market Value (February 2026)
Prices for triple SU setups have remained high due to the popularity of “de-smogging” later cars.
| Condition | Estimated Price (USD) | Notes |
| Used Mark X Setup | $1,500 – $2,800 | Often requires a full rebuild and “hisser” removal for E-Type use. |
| Used E-Type Setup | $4,000 – $6,000 | High demand for genuine Series 1 units; price depends on linkage completeness. |
| Restored/Remanufactured | $7,500 – $8,500 | Vapor-blasted bodies, rebushed spindles, and polished dashpots. |
| Full New Conversion Kit | $9,200 – $11,500 | Brand new SU units, polished manifold, and all linkages (e.g., SNG Barratt/Midel). |
3. Key Components for a Complete Set
A proper triple SU setup is more than just the three carburetors; it is a complex assembly of five major castings:
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Three Intake Manifolds: Individual runners for the front, center, and rear.
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Water Rail: The long casting that connects the manifolds to the thermostat housing.
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Vacuum Balance Pipe: The thin tube connecting the intake paths to ensure a smooth idle.
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Throttle Linkage: A complex set of rods, levers, and return springs. Note that 4.2L linkage is typically bottom-actuated, while 3.8L is top-actuated.
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Fuel Rail: The three-way brass or steel pipe that feeds fuel to each float bowl.
4. Technical Checklist
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Needle Selection: The standard needle for a 4.2L E-Type is usually the UM, while the 3.8L often uses a UE. For high-performance builds, the UVR is a popular modern choice.
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The “Drop Test”: Test used carbs by lifting the piston and letting it fall. It should fall smoothly with a clear metallic “thud.” If it sticks, the suction chamber and piston (which are a factory-matched pair) are likely warped or damaged.
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Thermostat Housing: Ensure the manifold includes the correct thermostat housing for your radiator hose orientation, as these varied across different Jaguar models.
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