Dual 40 HPMX Carburetor Kit, By EMPI

OVERVIEW

Unlock the true performance potential of your air-cooled engine with the EMPI Dual 40 HPMX Carburetor Kit. This kit is widely recognized by VW enthusiasts as the gold standard for street-level performance upgrades, providing a significant boost in horsepower and torque compared to a restrictive single-carburetor setup. The HPMX series is engineered to deliver precise fuel metering and exceptional throttle response, making it the perfect choice for daily drivers and weekend warriors alike. By utilizing two 40mm carburetors, your engine breathes more efficiently, allowing for a much broader power band and a smoother idle once properly synchronized. Whether you are cruising the local strip or navigating winding backroads, the Dual HPMX setup provides that iconic dual-throat growl and the aggressive acceleration that air-cooled owners crave.

This comprehensive kit from EMPI is designed to be a "bolt-on" solution that includes nearly everything you need to transform your engine bay. It features high-quality cast aluminum intake manifolds that are port-matched for optimal airflow, and a heavy-duty aluminum aircraft-style hex-bar linkage that ensures consistent throttle timing across both banks of cylinders. One of the greatest advantages of the HPMX line is its compatibility with standard Weber IDF jets, meaning you have access to a massive library of tuning components to dial in your specific engine displacement and altitude. While the kit provides a massive leap in performance, please note that because of the wider footprint of the dual carburetors, some modifications to the stock fan shroud or engine tin may be required to achieve a perfect fit. When you are looking for the ultimate balance of reliability and raw power, the EMPI 47-7317-0 kit stands as the premier choice for the serious VW builder.

FITMENT

• Volkswagen Type 1 Beetle: 1967-1977 (Dual Port Engines)
• Volkswagen Type 1 Super Beetle: 1971-1979
• Volkswagen Type 2 Bus: 1967-1971 (1600cc Dual Port Engines)
• Volkswagen Karmann Ghia: 1967-1974 (Dual Port Engines)
• Volkswagen Thing (Type 181): 1973-1974
• Custom Applications: Suitable for 1600cc to 1914cc Type 1 based upright engines

SPECS

• Carburetor Model: Dual EMPI 40 HPMX (Weber IDF Style)
• Venturi Size: 28mm
• Main Jets: 115
• Air Correction Jets: 200
• Idle Jets: 52
• Exhaust Pump Jet: .550
• Accelerator Pump Jet: .50
• Manifolds: Cast Aluminum Dual Port
• Linkage: Hex-Bar Aluminum Aircraft Style
• Air Cleaners: Chrome-topped with high-flow gauze elements
• Hardware: Includes gaskets, studs, and mounting hardware
• Fuel Compatibility: Compatible with standard pump gasoline

PRO TIPS

Tip 1: Fuel Pressure is Critical. One of the most common mistakes when installing HPMX or IDF style carburetors is running too much fuel pressure. These carburetors are designed to operate optimally at approximately 2.5 to 3.0 PSI. Most stock or high-performance mechanical pumps can spike higher than this, which can cause the needle and seat to unseat, leading to flooding and poor idle quality. We highly recommend installing a high-quality fuel pressure regulator between the pump and the "T" fitting to ensure a steady, low-pressure flow for consistent performance.

Tip 2: Synchronize for Success. You cannot tune a dual carb setup by ear alone. To get the smooth idle and crisp transition this kit is capable of, you must use a "Snail" style Uni-Syn or electronic synchronizer tool. Start by backing off the linkage so each carburetor is independent, then adjust the idle air bypass screws until both carburetors are pulling the exact same volume of air at idle. Only after they are synchronized should you reattach and adjust the hex-bar linkage to ensure both throttles open at the exact same moment.

Tip 3: Check Your Shroud Clearance. Because the 40 HPMX carburetors sit wider than a single carb, they often interfere with the "ears" of a stock VW fan shroud. Before final installation, test fit the carburetors on the manifolds. You may need to slightly dimple or trim the fan shroud tin to allow the linkage and air cleaners to sit level. Ensuring that the linkage moves freely without rubbing against the shroud is vital for safety and to prevent the throttle from sticking open during spirited driving. Don''t forget to use a small amount of Loctite on the linkage set screws to prevent them from vibrating loose over time.