Mercury’s WH-series carburetors were originally fitted to 2.0L and 2.4L V6 two-stroke outboards, including early Black Max models as well as the XR2 and XR4. Their strong midrange response and straightforward serviceability made them a mainstay through the 1980s, and their usefulness hasn’t ended there.
Today, these carburetors are frequently repurposed on rebuilt 2.5L fishing engines and in competition settings such as Drag Racing, USF1, and APBA F200 race powerheads.
Maintaining these carburetors requires fresh gaskets and precise fuel control, but many of the original Mercury service kits have been discontinued. The Mercury WH Full Carburetor Gasket, Needle & Seat Rebuild Kit 1395-6452is the essential foundation for keeping WH carburetors in service.
This rebuild kit provides the essential components to restore one WH carburetor to proper working order. To complete an entire V6 rebuild, three (3) kits are required—one for each carburetor.
Kit Overview
The kit contains all the gaskets, seals, and a new needle-and-seat assembly to service a single carburetor. These components cross-reference with Mercury OEM part numbers 1395-6026, 1395-6452, 1395-6452B, and aftermarket Sierra S18-7005.
With three (3) kits, you’ll have everything required to refresh a full bank of WH carburetors, restoring consistent fuel delivery and sealing integrity.
Outboard Carb Series Fitment
This kit supports nearly the full range of WH carburetor models, including WH-2, WH-3, WH-7, WH-12, WH-14, WH-15, WH-18, WH-20, WH-21, WH-22, WH-23, WH-26, WH-27, WH-28, WH-29, WH-31, WH-35, WH-38, WH-39, WH-40, WH-46, and WH-48.
Originally, these carburetors were factory-fitted on Mercury’s Black Max 150 and 175 hp, the XR2 150, the XR4 150, and early 200 and 220 hp V6 engines. They also appear on Bridgeport 2.4L models and continue to be a proven choice for 2.5L race builds where their airflow and booster signal support both acceleration and sustained top-end operation.
Installation and Float Height
Successful rebuilding requires precise setup, particularly when setting float height. All gasket surfaces should be cleaned carefully with non-metallic scrapers, and the needle seat bore must be spotless before installing the new seat. The float should pivot freely on its hinge pin with no side interference.
Float height is best set with the carburetor inverted. Measure at the float toe when the needle just contacts the seat but does not compress the spring. Buckshot Racing #77 recommends that all three carburetors be adjusted to the same height within .020 inches.
Small differences here translate to noticeable fueling imbalance across cylinders. Float drop must also be checked, ensuring the float does not allow the needle to slam open abruptly under acceleration or wave impact.
Synchronization of the linkage on reinstall on all three carburetors is vital to achieving a smooth idle and crisp throttle pickup.
On engines like the Black Max, XR2, and XR4, this rebuild restores the idle quality and midrange punch that made these motors so popular. On 2.5L drag and competition builds, WH carburetors continue to deliver reliable fueling when floats are matched and jetting is dialed for the application. Racers often rely on reading piston tops, plug, EGTs, and max RPMS to fine-tune jetting once the carburetors are mechanically correct.
Common Issues Solved by Carb Rebuilding
Rebuilding with fresh gaskets and needles eliminates many of the issues common to aging WH carburetors. Lean sneezing at idle, fuel seepage at bowl seams, midrange surging, and starvation at sustained high RPM are all often linked to worn gaskets or sticking needles. Once these components are replaced, the carburetors return to stable operation and predictable tuning.
Each kit services a single carburetor, and three (3) kits are required to refresh a full V6. Whether restoring a 150 Black Max, fine-tuning an XR2 or XR4, or preparing a 2.5L race powerhead for drag, USF1, or APBA F200 competition, fresh sealing and fuel control components are critical to performance and reliability.
For detailed advice, racer-level setup insights, or questions on jetting, contact Mike Hill at +1-714-697-1716 or mike@buckshotracing77.com.