Emulsion Tube, F4, for IDF, HPMX, DCOE DCO, EPC Carbs

OVERVIEW

Precision fuel metering is the cornerstone of a high-performance air-cooled engine, and the EMPI Emulsion Tube (F4) is the critical component that dictates how your fuel and air mix within the main circuit. Designed for the iconic Weber IDF and DCOE series, as well as the EMPI HPMX and EPC performance carburetors, the F4 emulsion tube is engineered to refine the atomization process. When your VW Beetle, Karmann Ghia, or Sand Rail demands a specific fuel curve to eliminate flat spots during acceleration, the emulsion tube is the first place a master tuner looks. The F4 profile is specifically utilized to control the timing and volume of air bleed into the fuel well, ensuring that as your RPMs climb, your engine receives a consistent, perfectly emulsified charge for maximum combustion efficiency.

Crafted from high-grade, corrosion-resistant brass, these EMPI emulsion tubes are manufactured to exacting tolerances to ensure parity across all barrels of your carburetor setup. Whether you are running a dual 40mm HPMX kit on a street-bound 1600cc or a pair of 48mm IDFs on a high-revving 2332cc stroker, the consistency of your emulsion tubes is paramount. The F4 series is often the go-to choice for tuners looking to bridge the gap between the idle and main circuits, providing a smoother transition that prevents the dreaded "stumble" often associated with performance carburetor setups. By choosing genuine EMPI components from Appletree Automotive, you are investing in decades of air-cooled heritage and proven track performance, ensuring your engine breathes exactly the way it was meant to.

FITMENT

This F4 Emulsion Tube is designed for use in a wide variety of high-performance carburetors commonly found on air-cooled VW engines and other vintage applications:

• Weber Carburetors: IDF (40, 44, 48), DCOE (40, 45, 48, 50), and DCO series.
• EMPI Carburetors: HPMX (40, 44, 48) and EPC (48, 51) series.
• Vehicle Applications: Ideal for Volkswagen Type 1 Beetle (1950-1979), Type 2 Bus/Transporter, Type 3 Fastback/Squareback, Karmann Ghia, VW Thing (Type 181), and all custom Dune Buggies, Sand Rails, and Baja Bugs.
• Universal Performance: Fits any engine utilizing the aforementioned carburetor types, including Porsche 356/912 and various British/European sportscars.

SPECS

Technical specifications for the EMPI 43-5672-0 Emulsion Tube:

• Part Number: 43-5672-0
• Emulsion Tube Series: F4
• Material: Precision-Machined Solid Brass
• Circuit Type: Main Circuit Metering
• Compatibility: Fully interchangeable with Weber part number 61440
• Quantity: Sold Individually (Each)
• Function: Controls the air/fuel mix ratio across the mid-to-high RPM range
• Finish: Natural Brass

PRO TIPS

1. Solving the Transition Flat Spot

If you are experiencing a hesitation or a "flat spot" as you transition from the idle circuit to the main circuit (typically between 2,500 and 3,200 RPM), your emulsion tube choice is likely the culprit. The F4 tube has a specific hole pattern that delays or advances the introduction of air into the fuel column. If your engine feels like it''s "falling on its face" just as you hit the throttle, verify that your main jets and air correctors are sized properly for the F4 tube. Always remember that the emulsion tube acts as the "bridge" between your low-speed and high-speed operation; getting this right is the difference between a sluggish engine and a crisp, responsive throttle.

2. Symmetry is Critical for Synchronized Carbs

In a dual-carburetor air-cooled setup, symmetry is everything. Never mix and match emulsion tube profiles (e.g., running an F4 in one barrel and an F11 in another). Even small variations in the hole diameter or placement on the tube can cause one cylinder bank to run leaner or richer than the other. When upgrading or replacing tubes, we highly recommend replacing all tubes across both carburetors at the same time. This ensures that the signal from the venturi pulls fuel identically across all four intake ports, leading to a smoother idle, better fuel economy, and more consistent power delivery.

3. Maintenance and Precision Cleaning

The tiny bleed holes on the F4 emulsion tube are precision-drilled to specific diameters. Over time, old fuel can varnish or "gum up" these orifices, drastically altering your engine''s performance. When cleaning your carburetors, avoid using metal wires or drill bits to poke through the emulsion tube holes, as this can easily enlarge the opening and ruin the tube''s calibration. Instead, use a high-quality aerosol carburetor cleaner and compressed air to blow out the passages. If you see any signs of green corrosion or "verdigris" on the brass that cannot be easily removed, it is time to replace the tubes to ensure your air/fuel mapping remains accurate.