Idle Jet DGV, DFV, ICT, EPC 40

OVERVIEW

Precision tuning is the heartbeat of a high-performance air-cooled engine, and the EMPI .40 Idle Jet is a critical component for achieving that perfect stoichiometric balance. When you are running Weber DGV, DFV, ICT, or the popular EMPI EPC series carburetors, the idle jet is responsible for much more than just the engine''s behavior at a standstill. In fact, the idle circuit handles fuel delivery for a significant portion of your low-end acceleration and cruising speeds, often controlling the air-to-fuel ratio up to nearly 3,000 RPM. If your Volkswagen is suffering from annoying flat spots, hesitations when you tip into the throttle, or a "hunting" idle, upgrading or replacing your jets with these high-precision brass units is the most effective way to dial in your driveability and ensure your engine runs cool and efficiently.

Crafted to exacting tolerances, these EMPI idle jets are designed to provide consistent fuel flow without the turbulence or variances found in inferior, knock-off components. Whether you are running a single ICT on a stock 1600cc upright engine or a progressive DGV setup on a rugged off-road rail, the .40 size is a foundational tuning tool for leaner requirements or specific altitude adjustments. At Appletree Automotive, we know that air-cooled VWs are sensitive to even the smallest changes in vacuum and fuel delivery. That is why we offer these genuine EMPI jets, ensuring that every time you turn the key, your Beetle, Bus, or Ghia responds with the crisp, reliable throttle response that only a perfectly jetted carburetor can provide. Do not let a clogged or incorrectly sized jet ruin your weekend cruise; invest in the precision of brass and the legacy of EMPI performance.

FITMENT

This idle jet is designed for use with specific Weber and EMPI carburetor models frequently used on the following air-cooled Volkswagen applications:

• Volkswagen Beetle: 1950 through 1979 (Sedan and Convertible)
• Volkswagen Karmann Ghia: 1956 through 1974
• Volkswagen Bus / Type 2: 1950 through 1979 (Split Window and Bay Window)
• Volkswagen Type 3: 1962 through 1973 (Fastback, Squareback, Notchback)
• Volkswagen Thing: 1973 through 1974
• Carburetor Compatibility: Weber 32/36 DGV, 32/36 DFV, 34 ICT, and EMPI EPC 38/40 Series

SPECS

Below are the technical specifications for the EMPI Idle Jet to assist in your tuning calculations:

• Orifice Size: .40mm (.040)
• Material: High-Grade Precision Machined Brass
• Manufacturer: EMPI
• Part Number: 74403.040
• Thread Pitch: Standard Weber/EMPI Idle Jet Metric Thread
• Application: Idle and Progression Circuit Fuel Metering
• Quantity: Sold Individually

PRO TIPS

1. Solving the Off-Idle Stumble

One of the most common complaints among VW owners with ICT or DGV carburetors is a "flat spot" or hesitation when pulling away from a stoplight. This is almost always an issue with the progression circuit, which is governed by the idle jet. If your engine stumbles as you transition from the idle circuit to the main circuit, it usually means your idle jet is too small or partially clogged. Moving to a .40 or .45 jet can often smooth out that transition, providing a seamless increase in power without the jerking motion associated with a lean condition. Always check for vacuum leaks before changing jets, as a leak will mimic the symptoms of a lean jet.

2. Tuning for Altitude and Air Density

Jetting is not a "one size fits all" science because air density changes based on your elevation and the weather. If you are driving your air-cooled VW in high-altitude environments, like the Rocky Mountains, the air is thinner and contains less oxygen. In these cases, a smaller idle jet like the .40 is often necessary to prevent the engine from running too rich, which can foul spark plugs and cause sluggish performance. Conversely, if you are at sea level where the air is dense, you may need to step up in size to prevent a lean-running condition that can lead to increased engine temperatures and potential valve damage.

3. Proper Maintenance and Installation

Brass is a relatively soft metal, and these jets feature very fine internal orifices. Never use a wire or a metal pin to clean a clogged idle jet, as this can easily gouge the brass and permanently change the flow characteristics of the jet, rendering it useless. Instead, use a high-quality aerosol carburetor cleaner and compressed air to blow out any debris. When installing the jet into the carburetor body, ensure you use a screwdriver that fits the slot perfectly to avoid "mangling" the head. Tighten the jet until it is snug, but do not over-torque it, as you can strip the threads in the carburetor housing or snap the jet off entirely.