Sierra 18-1957-2 Exhaust Manifold for MerCruiser GM Big Block V8

The Sierra 18-1957-2 is a heavy-duty cast iron exhaust manifold designed as a direct replacement for MerCruiser GM Big Block V8 marine engines. This manifold fits MerCruiser GM 7.4L & 8.2L CID marine engines and is compatible with Mercruiser 330, 340, & 454 Magnum model engines.

Key Features:

• Interchangeable between port and starboard side for flexible installation
• Heavy duty cast iron construction with black painted finish
• Ideally suited for freshwater applications
• Replaces most Mercruiser GM/Chevy V8 Big Block center rise manifolds
• Includes all gaskets, short riser studs, drain elbow, and plugs

What's Included:

• Manifold and riser gasket
• Bottom water fitting with built-in drain
• All pipe plugs and mounting gasket

Replaces OEM Part Numbers: Mercruiser 89011A8, 807078A2, 807078A4, 807078A6, 807078T09, 807078T10; Mallory 9-40506; Osco 9011A; Sierra 18-1957, 18-1957-1. Also replaces select Barr, GLM, Mallory & Mercruiser Sterndrive manifolds.

This complete manifold kit provides everything needed for a professional exhaust manifold replacement on MerCruiser Big Block V8 engines. Note: Manifold mounting kit (P/N 18-8532) sold separately.