The Buckshot Racing #77 Carburetor Velocity Stacks are engineered for high-performance marine use and designed specifically for Mercury V6 two-stroke carbureted outboard engines, including 3.0 Liter carbureted models. These stacks are IHRA F1 approved and are built to improve inlet airflow into WH, WMV, and WMH carburetors by replacing restrictive factory intake components and aging cast parts.
Each set is precision-machined from 6061-T6 billet aluminum, then finished for marine durability. Compared to many traditional cast intake pieces, billet construction allows tighter control of the inlet shape and surface finish, which supports more consistent airflow and improved repeatability from motor to motor—especially on legacy performance setups that live at higher RPM.
Why velocity stacks matter on carbureted Mercury V6 two-strokes
A velocity stack is not just cosmetic. On a carbureted two-stroke, the shape of the inlet influences airflow stability and the pressure signal the carburetor “sees.” The Buckshot #77 stacks use an optimized bell-mouth entry to reduce turbulence as air enters the carb throat. Smoother inlet flow can improve throttle response, help stabilize fuel metering across changing RPM and load, and support cleaner transition from idle to midrange on performance engines.
Engineered design features for low-speed stability and even fueling
Buckshot Racing #77 velocity stacks incorporate proprietary details aimed at performance and drivability. The overcut geometry is designed to provide a more stable atmospheric reference to the carburetor’s idle and low-speed circuits, which can improve low-end behavior on engines that otherwise tend to load up. In addition, the built-in dual-air sharing bridge allows adjacent carburetors to share intake airflow, promoting more balanced inlet conditions across the carb bank.
That balance supports more consistent fuel delivery cylinder-to-cylinder—an important benefit on Mercury V6 two-strokes where mixture variation can show up quickly in plug color, idle quality, and holeshot consistency.
Direct-fit replacement for Mercury Racing 13443A1 carb plate assembly
These stacks are designed as a direct-fit alternative to the discontinued Mercury Racing one-piece cast aluminum CARB PLATE ASSY, OEM part number 13443A1. On many high-performance applications, the OEM 13443A1 carb plate replaced the factory sound attenuator air box, and it became a common component on classic race and performance packages. If you are replacing an original cast carb plate system, the Buckshot #77 modular velocity stack setup is built to deliver a similar bolt-on function with improved serviceability.
Proven in classic Mercury racing applications and series
Mercury carb plate and velocity stack systems are closely tied to legacy competition outboards and class names that racers still search today. These include SST-120, SST-140, Formula 1 (USF1), and APBA F200, along with a wide range of 2.0L, 2.4L, 2.5L, and 3.0L Mercury V6 race-class and performance motors that have run across UIM, APBA, OPC, and other competition series. Buckshot Racing #77 velocity stacks are built for that same performance environment—where throttle response, consistent fueling, and repeatable tuning are priorities.
Fitment and compatibility: 1976–2005 carbureted Mercury V6 outboards, including 3.0 Liter
The Buckshot Racing #77 velocity stacks are designed for carbureted Mercury V6 outboards using WH, WMV, or WMH carburetors, commonly covering model years 1976 through 2005. They are frequently used on engine families and search terms such as Mercury 135 HP, 150 HP, 175 HP, 200 HP, and 225 HP V6 engines in the 2.0 liter and 2.4 liter ranges, and on Mercury 245 HP performance builds in the 2.5 liter V6 family.
They are also commonly associated with popular consumer performance naming like Mercury Black Max, XR2, XR4, and XR6, as well as race-carb references such as SST-140 WH-31, SST-120 WH46, and WMV-5 setups. In addition, these stacks are compatible with carbureted Mercury 3.0 Liter V6 outboards that use the same WH/WMV/WMH carburetor families.
Because Mercury front-half and carb combinations can vary across years, rebuilds, and racing conversions, confirming by carb family and the intake components you are replacing is the most reliable approach.
Modular design that makes tuning and maintenance easier
One of the biggest advantages of the Buckshot #77 system is serviceability. Unlike the OEM integrated one-piece carb plate, this setup is modular, which improves access during routine work such as jetting changes, carb removal, and linkage service. That saves time in the shop and reduces the frustration that often comes with tuning and maintenance on integrated cast intake assemblies.
What you receive with the Buckshot Racing #77 kit
Each kit includes three billet velocity stacks that are glass-bead blasted for a clean surface and then anodized for corrosion resistance in harsh marine environments, with common color options including red, black, and blue. The kit also includes six center-pull carb caps to help keep dust, dirt, and sand out during trailering and storage, along with six stainless steel socket-head bolts for a clean, professional installation.
Built for serious two-stroke performance
If you are maintaining or upgrading a legacy Mercury V6 carbureted two-stroke, including 3.0 Liter carbureted models, Buckshot Racing #77 velocity stacks are designed for performance enthusiasts and racers who want high-quality billet parts, improved airflow behavior, and easier tuning access—without compromising fitment to classic WH, WMV, and WMH carburetor platforms.
Contact Mike Hill at +1-714-697-1716 or email mike@buckshotracing77.com for technical support.