NACHUAN Mercruiser Marine Carburetor — 2‑Barrel, 3.75×2 in Base, Electric Choke, Jets Preinstalled

The NACHUAN 2-barrel marine carburetor is a direct-replacement Mercruiser-style carb designed to fit many 2.5L–5.7L 2-barrel engines with an electric choke and a 3.75 x 2 inch base bolt pattern.

This aftermarket carburetor is sold new (not remanufactured) and arrives ready to install with #70.9 jets pre-installed, a short linkage fitted, and a side fuel inlet. It replaces part numbers 3310-864940A01, 3310864940A01 and 8M0045397 and is intended for Mercruiser Stern Drive and Mercury Marine installations. Before purchasing, compare your existing carburetor to the provided photos to confirm dimensions and bolt pattern, since this unit is not compatible with 3.25" bases.

Will this carburetor physically fit my Mercruiser engine?

Compatibility depends on bolt pattern, mounting geometry and fuel/air connections. This NACHUAN unit uses a base bolt pattern of 3.75 x 2 inches, so it will not fit carbs with a 3.25-inch pattern. It is commonly used on 2.5L and 3.0L 4-cylinder Mercarb applications and can also be adapted to some 4.3L, 5.0L and 5.7L 2-barrel setups with professional tuning.

• Check base bolt pattern: 3.75 x 2 in required.
• Compare mounting flange and linkages with product photos.
• Confirm fuel inlet position (side inlet) and electric choke compatibility.
• Professional tuning advised for optimal performance on larger engines.

What comes in the box and what is pre-installed?

The carburetor ships as a complete unit ready to mount, with jets installed and a short linkage attached. The package includes a set of extra jets shown in product images for tuning purposes and a longer linkage provided but not installed. No printed installation manual is included.

• #70.9 jets are installed at the factory.
• Extra jets included for custom tuning needs.
• Short linkage installed; long linkage supplied in box (not fitted).
• Unit is brand-new, not remanufactured, and packaged for immediate installation.

Do I need any special tools or instructions to install it?

Basic hand tools and familiarity with marine carburetor mounting are usually sufficient, but installation details vary by engine model. The product does not include step-by-step instructions, so watching model-specific online tutorials or consulting a mechanic is recommended. Proper tuning and choke hookup are important to ensure reliable operation.

• Have basic wrenches, screwdrivers, and gaskets ready.
• Follow fuel line safety and electrical choke wiring best practices.
• Seek professional tuning for optimal jetting and idle adjustments.
• Contact the seller with fitment questions before purchase if uncertain.

How does this unit compare to OEM replacement parts?

This aftermarket carb matches common Mercruiser part numbers and mirrors OEM mounting and fuel connections, but final performance depends on correct jetting and setup for your engine. It offers a cost-effective alternative to dealer parts while providing compatibility with many Mercarb 2-barrel systems. Keep in mind that adjustments might be necessary to reach the same driveability as an OEM-calibrated carb.

• Replaces 3310-864940A01, 3310864940A01, 8M0045397.
• Electric choke included, side fuel inlet layout preserved.
• Pre-installed jetting may need tuning for altitude or engine variations.
• New, not remanufactured — fresh components throughout.

Who this is for: boat owners, marine mechanics and DIY restorers who need a ready-to-install replacement carburetor for Mercruiser-style 2-barrel engines. It’s best suited to people who can confirm bolt pattern and mounting compatibility from photos, are comfortable with basic carburetor installation, or have access to professional tuning. If you need precise OEM calibration or mounting for a 3.25" base pattern, consider verifying fitment carefully before purchasing.