THUNDERMINGO Mercruiser Carburetor 2‑Barrel for 2.5L/3.0L 4‑Cyl — Electric Choke, 3.75x2" Base

THUNDERMINGO marine carburetor is a direct-replacement 2-barrel carb for many Mercruiser 2.5L and 3.0L 4‑cylinder stern drive engines, supplied with an electric choke, pre-installed jets, linkages and gaskets for a ready-to-tune installation.

This carburetor is built to match common Mercruiser OE patterns and comes with the fittings and hardware most mechanics expect: electric choke, side fuel inlet, pre-installed #70.9 jets plus spare jets, both short and long throttle linkages, and gaskets. It replaces OEM references such as 3310-864940A01, 3310864940A01 and 8M0045397 and uses a 3 3/4 x 2 inch base bolt pattern. It is intended for use on many Mercury Marine stern drive 2.5L and 3.0L two-barrel, four-cylinder setups — but it will not fit the smaller 3.25-inch base used on some early 2GC models.

How will this carburetor match my Mercruiser engine?

The THUNDERMINGO unit is engineered to fit the common base bolt pattern and function like the stock Mercarb on most 2.5L and 3.0L 2-barrel four-cylinder engines. Confirm the base bolt pattern and choke/fuel inlet orientation on your manifold before ordering. Early Mercruiser 2GC carburetors have a smaller base and will not accept this part without modification or an adapter.

• Replaces OEM #3310-864940A01 and similar part numbers.
• Base bolt pattern: 3 3/4 x 2 inches — not compatible with 3.25" bases.
• Electric choke and side fuel inlet match many Mercury Marine installations.
• Designed for 2.5L and 3.0L 4‑cylinder stern drives.

What tuning and parts are included out of the box?

The carburetor ships with jets already installed and includes additional jets for common tuning adjustments, plus both short and long throttle linkages and gaskets to simplify replacement. Jets and linkages let you adapt the unit to your engine’s setup and local conditions; final tuning may still be required to dial in performance and fuel economy.

• Pre-installed main jets: #70.9 for a baseline setting.
• Includes spare jets: #68 and #78 for richer or leaner tuning.
• Short linkage installed; long linkage supplied in the box for different throttle arrangements.
• Gaskets and mounting hardware included for a complete swap.

Are there special installation notes or compatibility warnings?

No printed installation instructions are provided, so plan to follow a trusted installation video or have a qualified mechanic install and tune the carburetor. Verify you do not have the early small 2GC base before purchase; if you do, an adapter or modification may be necessary. The unit is bench-tested but final adjustments are often needed after installation.

• No installation manual included — follow online guides or pro service.
• Not compatible with the rare small 3.25" 2GC base without modification.
• Tuning recommended after installation; fuel system checks advised.
• Carburetor supplied ready to install and tested at the factory.

Who is this for: This THUNDERMINGO carburetor is aimed at boat owners, marine mechanics and restoration projects replacing worn or damaged Mercruiser two-barrel carbs on 2.5L and 3.0L four-cylinder stern drive engines. If you need a near-direct replacement with electric choke, spare jets for tuning, and both linkages included, this unit offers a practical, serviceable option — provided your manifold uses the 3 3/4 x 2 inch bolt pattern and you’re prepared to tune or have a technician install it.