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Sierra 18-1908K Manifold Riser Spacer Kit for MerCruiser Stern Drives

Manufacturer

Sierra

<h3>Sierra: Six Decades of Marine Aftermarket Excellence</h3><p><strong>Sierra</strong> has spent nearly 60 years earning its reputation as one of the most trusted names in the marine aftermarket industry. Originally focused on engine and drive components for boats, the brand has grown into a comprehensive source for nearly everything a boater needs to keep their vessel running at its best — from precision instrumentation to complete engine rebuild hardware.</p><p>Now operating as a brand of Dometic, Sierra manages global aftermarket distribution from a 300,000 sq. ft. facility in Litchfield, Illinois. The Sierra brand today encompasses not only its flagship marine parts line but also well-established marine names like Shields and Moeller, offering boaters a broader catalog than ever before. Whether you own an outboard, inboard, or sterndrive, Sierra's engineering team designs products to meet or exceed OEM specifications.</p><h3>Precision Instrumentation You Can Trust on the Water</h3><p>One of Sierra's most recognized product areas is its marine instrumentation lineup. The brand's <a href="/7570-sierra-gauge-set-1480">gauge sets</a> cover everything from classic analog instrument clusters to advanced digital multi-function displays. Sierra offers packages suited to outboards, sterndrives, and gasoline-powered inboards, with options ranging from coordinated analog kits in styles like Arctic, Eclipse, and Amega to modern touchscreen solutions like the R3 multi-function gauge. Features such as scratch-resistant domed glass lenses, silicone-dampened pointers, and perimeter backlighting make these instruments highly readable in all conditions.</p><p>Behind every accurate gauge reading is a properly calibrated sending circuit. Sierra's <a href="/7570-sierra-gauge-resistor-47908">gauge resistors</a> are a critical part of that chain, ensuring the signals from sensors and sending units are correctly interpreted by your instruments. These components are built to marine-grade standards to resist moisture, vibration, and corrosion — the realities of life on the water.</p><h3>Engine Internals Built to OEM Standards</h3><p>Sierra's history in marine power is perhaps best demonstrated by its deep catalog of engine components. The brand's <a href="/7570-sierra-engine-gasket-set-5404">engine gasket sets</a> cover a wide range of outboard and inboard applications and are engineered to deliver reliable seals in the demanding thermal and chemical environment of a marine engine. For boaters performing seasonal overhauls, top-end rebuilds, or full engine restorations, Sierra gasket kits are a go-to resource trusted by professional marine technicians and DIY boaters alike.</p><h3>A Complete Marine Parts Partner</h3><p>Beyond instrumentation and engine internals, Sierra's catalog spans fuel systems, electrical supplies, steering components, shore power, and more — all covered by what the brand calls an industry-leading warranty. Sierra also maintains a comprehensive parts-finder tool that enables cross-referencing with OEM part numbers from major manufacturers including Mercury, Yamaha, Suzuki, Volvo Penta, and others, making it straightforward to find the right replacement part for virtually any application.</p>

Part Number

18-1908K
05/07/2036 9:35 AM
Sale Price

$377.12

In Stock (10+)

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Usually delivered within 2 days

free shipping

FREE SHIPPING

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No Hassle Returns

No Hassle Returns

Live-in-stock inventory

Live-in-stock inventory

Fitment guaranteed

Fitment guaranteed

Product Details

The Sierra 18-1908K Manifold Riser Spacer Kit is a complete 3-inch riser extension system designed for MerCruiser V-6 marine engines with 2-piece exhaust manifolds. These extensions provide critical extra height to prevent water from traveling back into the riser when throttling down, while also offering added clearance for exhaust hose routing.

Key Features:

  • Engineered for GM-based V6 marine engines (229 and 262 cu.in.) with 2-piece exhaust manifolds
  • Machined mating surfaces eliminate additional preparation for proper sealing
  • Each riser extension is leak tested prior to painting to ensure quality
  • Uniform wall thickness created through special casting techniques
  • Primed and painted for durability and corrosion protection

Complete Kit Includes:

  • Two 3-inch riser spacer extensions (port and starboard)
  • Threaded rods and mounting hardware
  • Gaskets and pipe plugs
  • Ready to install out of the box

This kit replaces OEM part numbers 93320A13, 93320A6, 93320A5, 93320A3, 93320A2, and 807476A6. Compatible with MerCruiser models 185 and 205 (V-6 carbureted and TBI engines with serial numbers 0M614999 and below). Sierra engineers parts to meet or exceed manufacturer specifications, backed by SeaStar Solutions Limited Two-Year Warranty.

Products specifications

Application

Marine Power small block V8 305, 350, 4.3L, 454, 5.0L, 7.4L & 8.2L. Complete with mounting hardware and 3" center rise. Use with manifold 19521

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