0508878 Exhaust Manifold Gasket for OMC Cobra 7.4L 8.2L
0508878 Exhaust Manifold Gasket for OMC Cobra 7.4L 8.2L is backordered and will ship as soon as it is back in stock.
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0508878 Exhaust Manifold Gasket for OMC Cobra 7.4L 8.2L
0508878 Exhaust Manifold Gasket for OMC Cobra 7.4L 8.2L is backordered and will ship as soon as it is back in stock.
SERDAMARINE / MARINE EXHAUST PARTS
0508878 Exhaust Manifold Gasket for OMC Cobra 7.4L 8.2L
Aftermarket exhaust manifold gasket referenced to OMC 0508878 for 7.4L / GM 454 and 8.2L / GM 502 V8 applications from 1991 onward. Other valid references include 0778127 and 0909613.
Engine Applications
- OMC Cobra 7.4L / GM 454 and 8.2L / GM 502 V8; 1991 onward; match the exhaust manifold sealing interface.
- Chevrolet / Chevy 454 and 502 engine-base applications with the specified marine exhaust manifold.
Reference Numbers
The public part numbers below are provided as identification references and do not by themselves establish universal interchangeability or original-equipment manufacturer origin. Check the complete part number, including any prefix and A1 suffix, when comparing references.
| MerCruiser Reference Numbers | 27-46820, 27-46820A1, 46820, 46820A1 |
|---|---|
| Volvo Penta Reference Number | 3852472 |
| OMC Cobra Reference Numbers | 0508878, 0778127, 0909613, 508878, 778127, 909613, 3852472 |
| Crusader Reference Number | 96653 |
| Sierra Aftermarket Reference | 18-0418 |
| GLM Aftermarket References | 33760, 37760 |
| Mallory Aftermarket Reference | 9-61400 |
Supplied Parts
- Exhaust manifold gasket
Service & Installation Notes
General service guidance only. Use the service manual for your exact engine and exhaust configuration.
- Ensure the engine is completely shut off, cool to the touch, and secured against accidental starting before servicing any exhaust components.
- Support heavy exhaust manifold castings during disassembly and reassembly, and clean both mating surfaces thoroughly without gouging the sealing faces.
- Verify the installation position and gasket orientation; an exhaust manifold gasket and an exhaust elbow/riser gasket are separate parts. In a two-piece Ford 460-to-GM 454 manifold conversion arrangement, position this gasket between the adapter plate and the GM exhaust manifold.
- Follow your engine manufacturer's service manual for fastener tightening sequences and specifications. After reassembly, inspect the joint during initial operation and shut down immediately to inspect if any exhaust or cooling abnormality appears.
The Serdamarine Approach
Exhaust parts need a configuration match. Serdamarine focuses on marine exhaust manifolds and their related service parts. Application details, connection requirements and public reference numbers are presented together to support part selection.
Questions Before Replacement
Can this gasket be used on any Ford 460 marine engine?
No. On Ford 460 installations, it applies only to the adapter-plate-to-GM-exhaust-manifold joint in a two-piece Ford 460-to-GM 454 manifold conversion assembly. It is not a standard cylinder-head-to-Ford-manifold gasket.
What are Sierra numbers 18-1957-2, 18-1982, 18-1929, 18-1933, and 18-1898?
Those are Sierra exhaust manifold part numbers associated with gasket reference 18-0418. They identify compatible exhaust manifolds rather than engine models or direct cross-reference numbers for the gasket itself.
Related Service Parts
Sierra gasket reference 18-0418 is documented for use with Sierra exhaust manifold references 18-1957-2, 18-1982, 18-1929, 18-1933, and 18-1898. Exhaust manifolds and exhaust elbow/riser gaskets are separate components and are not included with this gasket.
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