Main Jet DGV, DFV, ICT EPC 170

Experience Precision Fueling with the EMPI 170 Main Jet

When it comes to dialing in the performance of your air-cooled Volkswagen, nothing is more critical than the air-fuel mixture. The EMPI 170 Main Jet for DGV, DFV, ICT, and EPC carburetors is a precision-engineered component designed to provide the exact fuel flow required for high-performance tuning. Whether you are running a classic Weber 32/36 Progressive or a dual 34mm ICT setup, the main jet is the heart of your carburetor''s high-speed circuit. A 170 jet is often the "sweet spot" for engines with moderate modifications, such as upgraded camshafts or higher compression ratios, where the standard factory jetting simply cannot keep up with the increased volumetric efficiency. By installing a genuine EMPI jet, you ensure that your engine receives a consistent, atomized fuel supply, preventing lean-out conditions that can lead to overheating, melted pistons, and catastrophic engine failure.

At Appletree Automotive, we know that every engine build is unique, and "off-the-shelf" carburetor settings rarely deliver maximum horsepower or optimal fuel economy. This 170 main jet allows you to fine-tune your fuel curve to match your specific displacement, altitude, and driving style. Precision-machined from high-quality brass, these jets feature consistent internal diameters and smooth flow characteristics that cheap knock-offs simply cannot replicate. If you have noticed a flat spot in your acceleration or your spark plugs are showing a white, lean color after a high-speed run, it is time to step up your jetting. Investing in a range of main jets is the mark of a true VW enthusiast who understands that the difference between a "runner" and a "screamer" lies in the smallest details of the venturi circuit.

Detailed Fitment and Compatibility

This main jet is designed for a wide array of Weber and EMPI carburetor families commonly found on air-cooled Volkswagens and other vintage applications. Fitment includes:

• Weber DGV Series: Fits 32/36 DGV, DGAV, and DGEV Progressive carburetors.
• Weber DFV Series: Fits 32/36 DFV, DFAV, and DFEV carburetors.
• Weber ICT Series: Fits 34 ICT single-barrel carburetors (often used in dual kits).
• EMPI EPC Series: Fits EMPI 34 EPC carburetors, the popular choice for dual-carb Beetle and Bus setups.
• Holley Weber: Compatible with various Holley-licensed versions of the DGV/DFV platform.
• VW Type 1 Beetle: 1954 through 1977 (Sedan and Convertible) equipped with aftermarket Weber/EMPI carbs.
• VW Type 2 Bus: 1950 through 1979 (Split Window and Bay Window) utilizing ICT or Progressive setups.
• VW Type 3: Notchback, Fastback, and Squareback models running dual ICT or EPC carburetors.
• VW Karmann Ghia: 1956 through 1974 models with upgraded fuel systems.
• Sand Rails and Manx Buggies: Ideal for custom off-road builds using Weber or EMPI carburetion.

Technical Specifications and Dimensions

The EMPI 170 Main Jet is manufactured to exacting standards to ensure repeatable performance across all cylinders.

• Jet Size: 170 (1.70mm calibrated orifice).
• Material: High-grade, corrosion-resistant yellow brass.
• Thread Type: Standard Weber/EMPI main jet threading for DGV/ICT/EPC housings.
• Orifice Precision: Micro-drilled and flow-tested for accuracy.
• Compatibility: Compatible with standard E10 pump gas, racing fuels, and non-ethanol blends.
• Manufacturer: EMPI (Part Number 73801.170).
• Quantity: Sold individually (Dual-carb applications require two).

Master Specialist Pro Tips for Carburetor Tuning

Tip 1: The "Plug Chop" Method for Main Jet Verification

To determine if the 170 main jet is correct for your engine, you must perform a "plug chop." Take your VW out to a safe stretch of road, accelerate through the gears, and hold the engine at a steady, high-RPM cruise (around 3,500 to 4,000 RPM) for at least 30 seconds. While still at speed, safely kill the ignition and coast to a stop. Pull your spark plugs and inspect the porcelain insulator. A light tan or "cardboard" brown color indicates that your 170 main jet is providing the correct mixture. If the porcelain is stark white, you are lean and may need to go up to a 175 or 180. If it is black and sooty, you are rich and should consider a smaller jet size.

Tip 2: Avoid Over-Tightening Brass Components

One of the most common mistakes I see in the shop is "gorilla-tightening" jets into the carburetor body. These jets are made of brass, which is a relatively soft metal. Use a high-quality, flat-head screwdriver that fits the slot perfectly to avoid marring the jet. You only need to snug the jet down until it seats firmly. Over-tightening can distort the jet orifice or, worse, strip the threads in the carburetor bowl. If you mar the slot, the resulting brass burr can actually disrupt the fuel flow into the jet, causing turbulence that ruins your tuning efforts. Always ensure your workspace is clinical-clean, as a single grain of sand can clog a 170 orifice instantly.

Tip 3: Coordinate with Air Correction Jets

Remember that the main jet does not work in a vacuum; it works in tandem with your air correction jet. The main jet controls the volume of fuel, while the air correction jet controls when that fuel begins to flow and how it leans out at very high RPMs. If you install this 170 main jet and find that the car runs great at mid-range but "stumbles" or falls flat at the top of the RPM band, you likely need to adjust your air correction jet. Generally, a larger main jet requires a slightly different air correction strategy to maintain a linear fuel curve. Tuning is a balancealways change only one variable at a time so you can accurately track your performance gains.