In tunnel boat racing, outboard drag racing, and high-performance offshore marine racing, fuel stability is essential for consistent power delivery.
Mercury Racing WH-series carburetors, such as the WH-46 (SST-120, 2.0 Liter), WH-31 (SST-140, 2.4 Liter), and WH-46 or WH-22 (XR2, 2.0 ROS Liter), are subjected to extreme fuel movement due to rapid acceleration, deceleration, and aggressive cornering.
Without slosh tubes, fuel inside the carburetor float bowls can shift uncontrollably, leading to fuel starvation, air bubble formation (aeration), and erratic throttle response.
When fuel moves away from the jets, the engine experiences lean conditions, misfires, and power loss. Slosh tubes help maintain a steady air/fuel mixture by directing fuel flow within the float bowl, preventing fuel surge and ensuring smooth performance under extreme racing conditions.
For racers competing in Mercury Racing 2.0 Liter, 2.4 Liter, and 2.5 Liter classes, nickel-plated brass elbow fittings by Buckshot Racing #77, replacing Mercury OEM 94090, are essential for proper slosh tube function.
These fittings require a secure press fit into the carburetor body. Our elbow fittings are ~.060", 1-2 thousandths oversized compared to old OEM 22-94090, ensuring a tight, reliable fit for extreme racing conditions.
The proper drill size depends on the material.
In aluminum carburetors, a #53 drill bit (0.0595") or 1.50 mm (0.0591") provides a light press fit, while a 1.45 mm (0.0571") drill bit ensures a tighter press fit.
For steel components, a 0.058"-0.0585" hole offers a secure fit without excessive force. If a hole is too loose, JB Weld or high-strength retaining compound can restore a tight, leak-free seal.
Proper slosh tube placement is key to ensuring effective fuel control in Mercury Racing WH carburetors. The elbow fittings should be pressed into the upper vent passages of the float bowl, specifically into the vent hole near the top of the carburetor, aligning to channel fuel movement efficiently.
A Tygon F-4040-A type fuel bleed line should be routed from the elbow fitting to the float bowl, helping prevent sudden fuel displacement during tunnel boat racing or outboard drag racing.
Ensuring precise press fit and correct placement stabilizes fuel levels, enhances throttle response, and eliminates power loss caused by fuel movement.
By installing slosh tubes correctly, racers can optimize the performance and reliability of their Mercury Racing 2.0L, 2.4L, and 2.5L WH-series carburetors, making them an essential upgrade for high-performance outboard racing applications.
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