Emulsion Tube, F15, for IDF, HPMX, DCOE DCO, EPC Carbs

OVERVIEW

Precision fuel delivery is the heartbeat of any high-performance air-cooled engine, and the EMPI F15 Emulsion Tube is a critical component for tuners seeking to eliminate flat spots and optimize the transition between the idle and main circuits. Designed to fit a wide array of performance carburetors including the Weber IDF, EMPI HPMX, and the legendary DCOE side-draft series, the F15 profile is specifically engineered to control the aeration of fuel as it travels from the main jet toward the venturi. By utilizing a strategic arrangement of bleed holes, this emulsion tube dictates exactly when and how much air is mixed with the raw fuel, ensuring that your Volkswagen or high-output sand rail doesn''t stumble when you mash the throttle. Whether you are building a street-screaming 2110cc Beetle engine or a rugged off-road powerplant, the F15 provides the nuanced calibration required to handle the specific vacuum signatures of performance camshafts and high-flow cylinder heads.

At Appletree Automotive, we understand that "close enough" isn''t good enough when it comes to carburetor jetting. The EMPI 43-5680-0 emulsion tube is manufactured to exacting tolerances from high-quality brass to prevent corrosion and ensure long-term dimensional stability. While the F11 is often the "out of the box" standard for many dual-carb kits, the F15 offers a distinct enrichment curve that is frequently favored by master tuners for engines that require a slightly different fuel-to-air ratio during mid-range acceleration. Replacing worn or incorrectly sized tubes with these genuine EMPI units allows for a crisp, linear power delivery that enhances the overall drivability of your vintage VW. Don''t let a mid-range bog ruin your driving experience; upgrading to the correct emulsion tube profile is one of the most cost-effective ways to fine-tune your induction system for peak efficiency and maximum horsepower.

FITMENT

This F15 Emulsion Tube is designed for use in the following carburetor models and air-cooled Volkswagen applications:

• Carburetor Models: Weber IDF (40, 44, 48), EMPI HPMX (40, 44, 48), Weber DCOE Side-draft, Weber DCO, EMPI EPC 48/51, and Weber IDA (2-Barrel and 3-Barrel).
• VW Beetle (Type 1): 1950 through 1979 models equipped with aftermarket dual carburetors.
• VW Karmann Ghia: 1956 through 1974 performance builds.
• VW Bus / Transporter (Type 2): 1950 through 1979, specifically Type 4 engine conversions using IDF or HPMX setups.
• VW Type 3 (Squareback, Fastback, Notchback): 1961 through 1973 dual-carbureted configurations.
• Custom Applications: Dune Buggies, Sand Rails, Manx clones, and kit cars using any of the aforementioned carburetor series.

SPECS

• Part Number: 43-5680-0
• Emulsion Tube Series: F15
• Material: Precision-Machined Solid Brass
• Application: Main Circuit Fuel/Air Mixing
• Compatible Brands: EMPI, Weber, Solex (select models)
• Quantity: Sold Individually (Each)
• Design Function: Controls the "timing" of air-fuel mixture enrichment via calibrated bleed holes

PRO TIPS

Tip 1: Sync Your Circuitry for Symmetry. When installing new F15 emulsion tubes, it is imperative that you replace them across all barrels of your carburetor setup simultaneously. Even a slight variation in the tube profile or hole diameter between cylinders can lead to uneven combustion temperatures and a "rough" feel under load. Always verify that your air corrector jets, which sit directly on top of these emulsion tubes, are also matched across the engine to ensure that each cylinder is receiving the exact same air-fuel mixture profile.

Tip 2: Understand the Air Corrector Relationship. The emulsion tube does not work in a vacuum; its performance is heavily dictated by the size of the air corrector jet installed above it. If you find that your engine is still leaning out too much at high RPMs despite using the F15, you may need to decrease the size of your air corrector jet. Conversely, if the top end feels "lazy" or overly rich, a larger air corrector jet will allow more air into the F15 tube, leaning out the mixture as the engine speed increases. Tuning is a balance between the main jet, the emulsion tube, and the air corrector.

Tip 3: Cleanliness is Critical for Calibration. The tiny bleed holes along the shaft of the F15 emulsion tube are what define its "F" rating. Over time, fuel varnish or debris can partially clog these holes, which will completely change the enrichment curve of the tube and lead to mysterious flat spots that are hard to diagnose. Whenever you have your carburetors open for a seasonal tune-up, remove the emulsion tubes and clean them with high-quality carburetor cleaner and compressed air. Never use a metal wire to poke through the holes, as this can enlarge them and permanently ruin the calibration of the tube.