THUNDERMINGO Marine Carburetor for Mercruiser 3.0/2.5L 2‑Barrel — Electric Choke, Long Linkage Included

This carburetor is built to match common Mercruiser 3.0 and 2.5 liter 4‑cylinder applications that use the 2‑barrel Mercarb design. It ships with a long linkage in the box (short linkage installed), a side fuel inlet, #70.9 jets preinstalled, and four additional jets (#68 and #78) for tuning. The base bolt pattern measures 3 3/4 x 2 inches, so confirm your base size before ordering: early Mercruiser models used a smaller 3.25‑inch base and are not compatible without modification or an adapter.

Will this carburetor fit my Mercruiser or Mercury engine?

Fitment is for 2‑barrel Mercruiser/Mercarb 3.0L and 2.5L 4‑cylinder engines that accept a 3 3/4 x 2 inch carburetor base. It is not compatible with the rare small 3.25‑inch base carburetors used on some early models. Measure your carburetor base bolt pattern or compare part numbers before purchase.

• Compatible replacement part numbers: 3310‑864940A01 and 8M0045397.
• Base bolt pattern: 3 3/4 x 2 inches — confirm match before ordering.
• Intended for Mercruiser stern drive and Mercury Marine Mercarb 2‑barrel setups.

What comes in the box and which adjustments are included?

The carburetor arrives ready with a short linkage installed and a long linkage included in the package for different throttle arm geometries. A gasket is supplied and the electric choke is fitted. Jets are preinstalled (#70.9) and extra jets (#68 and #78) are provided to tune fuel mixture for your rig.

• Installed: short linkage, electric choke, #70.9 main jets.
• Included: long linkage, extra jets (#68 and #78), gasket.
• Side fuel inlet configuration to match many Mercury fuel lines.

How should I install and tune this carburetor for best results?

No printed installation instructions are included, so follow trusted service videos or a factory manual for step‑by‑step guidance. The unit is fully tested at the factory and ready to install, but engines frequently require tuning to match local altitude, propeller load, and ignition timing. If you’re not experienced with carburetor synchronization and jetting, have a qualified marine mechanic perform the final setup.

• Verify fitment and clearances before installing.
• Install gasket and secure base bolts to specified torque values from your service manual.
• Use the supplied extra jets for fine tuning; check AFR and performance under load.

Are there any fitment warnings or special considerations?

Early Mercruiser models used a smaller 2GC carburetor (3.25‑inch base) which this unit will not fit without modification or an adapter. Also confirm throttle linkage orientation and choke wiring compatibility before purchase. If in doubt, compare the replacement part numbers listed to the carb on your engine.

• Not compatible with 3.25‑inch base carburetors unless modified.
• Long linkage provided if your throttle arm requires it; check linkage geometry.
• No installation manual included — follow professional guidance or video tutorials.

Who is this for: This THUNDERMINGO carburetor is aimed at boat owners, marine mechanics, and restoration enthusiasts replacing or upgrading a 2‑barrel Mercarb on 2.5L or 3.0L Mercruiser 4‑cylinder stern drive engines. Choose this unit if your engine uses the 3 3/4 x 2 inch bolt pattern and you want a complete replacement that includes an electric choke, extra jets for tuning, a gasket, and both linkage options for easier fitment.