Sierra 18-7201 Brass Carburetor Float for Rochester 4MV 4-Barrel Carburetors, Replaces Mercury Marine 1397-8546

The Sierra 18-7201 is a brass carburetor float built as a direct-fit replacement for Rochester 4MV (Quadrajet-style) 4-barrel marine carburetors. The float is machined brass, chosen for its alcohol-resistant properties so it holds a stable, accurate fuel level in ethanol-blended pump gas without swelling, absorbing fuel, or losing calibration over time the way some composite or plastic floats can. A correctly functioning float is what keeps the carburetor's fuel bowl at the proper level; a worn, waterlogged, or out-of-spec float leads to flooding, hard starting, rough idle, or fuel starvation at speed, so this is a common wear item to inspect and replace during a carburetor rebuild.

This float is designed for GM 4.3L and 5.0L marine engines built between 1979 and 1989 that use the R4 4MV carburetor, and it pairs with the Sierra 18-7095 carburetor kit for that same application. It is intended to be installed as part of a rebuild alongside the correct kit rather than as a standalone repair. Sierra manufactures the 18-7201 as a direct equivalent to the OEM Mercury Marine and OMC float numbers it replaces, so it drops into the same carburetor bowl and pivot without modification.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-7201
• Product Type: Carburetor Float
• Material: Brass
• Finish: Machined
• Carburetor Compatibility: Rochester 4MV 4-barrel carburetor
• Engine Fitment: GM 4.3L and 5.0L, 1979-89, R4 4MV carburetor
• Companion Carburetor Kit: Sierra 18-7095
• OEM Cross Reference: Mercury Marine 1397-3327, 1397-8546, 1397-8959; OMC 383087, 983871
• Weight: 0.02 pounds
• UPC: 030999322135

Fitment

• GM 4.3L, 1979-89, R4 4MV carburetor
• GM 5.0L, 1979-89, R4 4MV carburetor

Replaces (OEM)

• Mercury Marine 1397-3327
• Mercury Marine 1397-8546
• Mercury Marine 1397-8959
• OMC 383087
• OMC 983871

Frequently Asked Questions

What carburetors does the Sierra 18-7201 float fit? The Sierra 18-7201 is built for Rochester 4MV 4-barrel carburetors used on GM 4.3L and 5.0L marine engines from 1979-89.

Is the 18-7201 float made of brass or plastic? It is machined brass, which resists swelling and absorption from ethanol-blended fuel, so the float level stays accurate over time compared to some composite floats.

Does the Sierra 18-7201 replace an OEM Mercury Marine float? Yes, it is a direct equivalent to Mercury Marine float numbers 1397-3327, 1397-8546, and 1397-8959.

Does the Sierra 18-7201 also cross to an OMC float number? Yes, it replaces OMC float numbers 383087 and 983871 in addition to the Mercury Marine numbers.

How much does the 18-7201 float weigh? The Sierra 18-7201 carburetor float weighs 0.02 pounds.

What carburetor kit should be used with this float? Sierra pairs the 18-7201 float with the 18-7095 carburetor kit for the same 4.3L and 5.0L, 1979-89, R4 4MV applications.

Can I install just the float without rebuilding the whole carburetor? The 18-7201 is sold as an individual float component and is intended to be installed during a carburetor rebuild alongside the matching 18-7095 kit rather than as a standalone fix.

Will this float work on a carburetor other than the Rochester 4MV? The Sierra 18-7201 is designed specifically for the Rochester 4MV 4-barrel carburetor used on the listed GM 4.3L and 5.0L engines; it is not specified for other carburetor models in Sierra's catalog.

Why does a carburetor float need to be replaced? A brass float like the 18-7201 can develop leaks or lose calibration with age, which raises or lowers the fuel bowl level and causes symptoms like flooding, hard starting, or rough idle.

Is the 18-7201 an OEM part or aftermarket? The 18-7201 is a Sierra-manufactured aftermarket float engineered as a direct equivalent to the original Mercury Marine and OMC float part numbers it replaces.

What finish does the Sierra 18-7201 float have? The float has a machined brass finish.

What years of GM marine engines use this float? The Sierra 18-7201 fits GM 4.3L and 5.0L marine engines built in the 1979-89 range with the R4 4MV carburetor.