Carburetor Mounting Gasket – Fits MerCruiser V8 225-390 HP (Replaces 27-48399)
Carburetor Mounting Gasket – Fits MerCruiser V8 225-390 HP (Replaces 27-48399) is backordered and will ship as soon as it is back in stock.
Couldn't load pickup availability
Worry-free returns
Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Product Details
This high-quality Carburetor Mounting Gasket ensures a perfect seal between the carburetor and intake manifold. It is specifically designed to fit a range of MerCruiser V8 engines from 225 to 390 HP, manufactured between 1967 and 1974, that use a Rochester 4-barrel carburetor.
This part offers a direct interchange for Sierra 18-0462, GLM 31540, and Mallory 9-61003, providing a reliable alternative to the original OEM part (27-48399), which is no longer available from the manufacturer.
- Installation Location: Mounts securely between the Rochester 4-barrel carburetor and the engine's intake manifold.
- Material: Manufactured from premium, OEM-specification gasket material for durability and a leak-free seal.
- Engine Application: Specifically for gasoline-powered MerCruiser V8 marine engines.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| MerCruiser (OEM) | 27-48399 |
| Sierra | 18-0462 |
| GLM | 31540 |
| Mallory | 9-61003 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For MerCruiser applications, verify your engine model and serial number range to ensure correct fitment.
| Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|
| 225 (2 BBL.) GM 327 V-8 | 225 | 4-Stroke | 1967–1969 | 27-48399 | Serial Range: 2278647-2694014 |
| 225 MIE GM 327 V-8 | 225 | 4-Stroke | 1968 | 27-48399 | Serial Range: 2278647-2694014 |
| 250 (2 BBL.) GM 327 V-8 | 250 | 4-Stroke | 1968–1969 | 27-48399 | Serial Range: 2314301-2639854 |
| 250 MIE GM 327 V-8 | 250 | 4-Stroke | 1968–1969 | 27-48399 | Serial Range: 2314301-2639854 |
| 250 (350 CID) V8 | 250 | 4-Stroke | 1977 | 27-48399 | Serial Range: 4768000-4908849, Carb #1347-3353, MFG Model #7037082 R4/4M V |
| 270 (2 BBL.) GM 350 V-8 | 270 | 4-Stroke | 1969–1972 | 27-48399 | Serial Range: 2851074-3077735 |
| 270 MIE GM 350 V-8 | 270 | 4-Stroke | 1969–1972 | 27-48399 | Serial Range: 2851074-3077735 |
| 325 GM 427 V-8 | 325 | 4-Stroke | 1969–1972 | 27-48399 | Serial Range: 2278747-3780449 |
| 325 MIE GM 427 V-8 | 325 | 4-Stroke | 1968–1974 | 27-48399 | Serial Range: 2278747-3780449 |
| 390 GM 482 V-8 | 390 | 4-Stroke | 1969–1970 | 27-48399 | Serial Range: 2781129-2825059 |
| 390 MIE GM 482 V-8 | 390 | 4-Stroke | 1969–1970 | 27-48399 | Serial Range: 2781129-2825059 |
Technical Specs
- Product Type
- Carburetor Mounting Gasket
- Installation
- Between carburetor and intake manifold
- Application
- Rochester 4-barrel carburetor mounting
- Fuel Type
- Gasoline
- Material
- OEM-specification gasket material
- Dimensions
- 17.0" L x 15.0" W x 0.5" H
- Country of Origin
- United States (Sierra replacement part)
- Warranty
- Limited lifetime (Sierra replacement part)
What’s in the Box
- 1 x Carburetor Mounting Gasket (Replaces 27-48399)
Installation Notes
- Ensure the engine is cool and disconnect the battery for safety.
- Relieve any pressure from the fuel system and disconnect the fuel lines from the carburetor.
- Remove the air cleaner assembly and any related hoses.
- Carefully detach all throttle linkages, choke connections, and vacuum hoses connected to the carburetor. Note their positions for reassembly.
- Unscrew the carburetor mounting bolts or nuts.
- Gently lift the carburetor off the intake manifold.
- Remove the old gasket and thoroughly clean any residue from both the carburetor base and the intake manifold surfaces. A clean, smooth surface is critical for a good seal.
- Position the new gasket on the intake manifold, aligning it with the mounting studs or bolt holes.
- Carefully place the carburetor back onto the new gasket.
- Tighten the mounting bolts or nuts in a crisscross pattern to the manufacturer's specified torque to ensure even pressure.
- Reconnect all fuel lines, linkages, and hoses.
- Reinstall the air cleaner assembly and reconnect the battery. Start the engine and inspect carefully for any fuel or vacuum leaks around the gasket.
Troubleshooting & FAQ
How do I know if this gasket fits my engine?
This gasket is designed for specific MerCruiser V8 models (225-390 HP) from 1967–1974 using a Rochester 4-barrel carburetor. Please cross-reference your engine model and year with our compatibility table. It is a direct replacement for OEM part 27-48399 and interchanges with Sierra 18-0462, GLM 31540, and Mallory 9-61003.
What are the signs of a faulty carburetor gasket?
Common symptoms of a failed carburetor mounting gasket include vacuum leaks (a hissing sound near the carburetor base), a rough or inconsistent idle, engine stalling, reduced fuel efficiency, and difficulty starting the engine due to an improper air-fuel mixture.
Can I reuse my old gasket or should I use a sealant?
No, gaskets are single-use components designed to crush and seal. Reusing an old gasket will likely result in leaks. This gasket is designed to be installed dry; applying sealant can interfere with its sealing ability and is generally not recommended unless specified by your engine's service manual.
Why is my engine running poorly after installation?
If you experience poor performance after installing the new gasket, first check for vacuum leaks around the carburetor base. Ensure the mounting bolts are torqued evenly and to the correct specification. Also, verify that all vacuum hoses and linkages were reconnected correctly to their original positions.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
