Twin 40IDF HPMX Carburettor Kit - Type 1 Twin Port Engines

High-performance twin EMPI 40 HPMX carburettor kit designed for Type 1 twin port aircooled engines, offering a cost-effective alternative to Weber IDF systems while delivering impressive power, adjustability and reliability.

The EMPI HPMX carburettors are engineered for precise fuel and air metering, using a dedicated butterfly per cylinder to maximise airflow and engine efficiency. This design allows for finer tuning compared to single carb setups, improving throttle response, torque and top-end performance. Internally, the carburettors feature separate idle and main circuits, with changeable jets and venturis to suit a wide range of engine builds.

Supplied with 28mm venturis, this kit is ideally suited to engines 1800cc and above, where increased airflow and fuel delivery can be fully utilised. The adjustable accelerator pump ensures strong off-idle response, while upgraded extended idle jet vent tubes help prevent common idle jet blockages, improving reliability in everyday use.

The included hex bar linkage system uses an aluminium cross bar with steel ball ends and sealed heim joints, providing smooth and consistent throttle operation across both carburettors.

Kit Includes

• 2 x EMPI 40 HPMX carburettors
• Aluminium hex bar linkage with heim joints
• Offset aluminium intake manifolds
• Chrome air filters with high-flow gauze elements
• Linkage mounts and hardware
• Fuel hose and brass fuel tee
• Coil relocation bracket
• Full fitting instructions

Jetting Specification (as supplied)

• 52 Idle Jets
• 115 Main Jets
• 200 Air Correctors
• F11 Emulsion Tubes
• 28mm Venturis
• 50 Accelerator Pump Jets

How It Works
Each carburettor feeds two cylinders, dramatically improving air/fuel distribution compared to a single carburettor. The adjustable jetting system allows precise tuning of idle, mid-range and high-speed circuits, while the accelerator pump enriches the mixture under sudden throttle input for improved acceleration.

Important Notes

• Designed for Type 1 twin port engines
• Best suited for engines 1800cc+
• Will NOT fit 1200cc engines
• No choke system (manual warm-up required)
• Rolling road tuning and synchronisation strongly recommended

Related Parts

• Carburettor balancing tool
• Fuel pressure regulator
• Performance ignition system
• Manifold gaskets and seal kits
• Throttle cable and linkage components

To Fit

Aircooled VW

• VW Beetle – 1960–1979 – Type 1 twin port engines (recommended 1800cc+)
• VW T2 Splitscreen Bus – 1960–1967 – Type 1 twin port engines (recommended 1800cc+)
• VW T2 Baywindow – 1968–1979 – Type 1 twin port engines (recommended 1800cc+)
• VW Karmann Ghia – 1960–1974 – Type 1 twin port engines (recommended 1800cc+)
• VW Type 181 Trekker – 1968–1983 – Type 1 twin port engines (recommended 1800cc+)
• VW Beach Buggy / Baja – 1960–1979 – Type 1 twin port engines (recommended 1800cc+)