My Account
Shopping Cart

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

Manufacturer

Sierra

<p>For nearly six decades, Sierra has established itself as one of the marine industry's most trusted names in aftermarket engine and drive parts. Founded as a specialized marine parts manufacturer, Sierra has grown into a comprehensive supplier of replacement components, instrumentation, and accessories for both recreational and commercial boating applications. Operating from their 300,000-square-foot distribution center in Litchfield, Illinois, Sierra serves boat owners and marine technicians worldwide with an extensive catalog of parts engineered specifically for the harsh saltwater environment.</p><h3>Marine Engine Excellence</h3><p>Sierra's reputation was built on delivering precision-engineered internal engine components and drive system parts that meet or exceed OEM specifications. Their <a href="/7570-sierra-engine-gasket-set-5404">engine gasket sets</a> provide critical sealing solutions for inboard and outboard motors, while their <a href="/7570-sierra-engine-complete-assembly-15341">engine complete assemblies</a> offer comprehensive replacement options for major overhauls. Each component undergoes rigorous testing to ensure reliability in demanding marine conditions, from corrosion resistance to temperature cycling performance.</p><h3>Instrumentation and Monitoring Systems</h3><p>Accurate instrumentation is essential for boat operators to monitor engine health and prevent costly breakdowns on the water. Sierra's comprehensive line of <a href="/7570-sierra-gauges-200483">gauges</a> includes everything from fuel pressure and temperature indicators to voltmeters and trim gauges, all designed with marine-grade materials that withstand vibration, moisture, and UV exposure. Their <a href="/7570-sierra-tachometer-gauge-1488">tachometer gauges</a> deliver precise RPM readings critical for optimizing engine performance and fuel efficiency. Supporting these instruments, Sierra's <a href="/7570-sierra-gauge-resistor-47908">gauge resistors</a> ensure proper signal conditioning and accurate readings across various sensor types and engine configurations.</p><h3>Expanded Product Portfolio</h3><p>In 2022, Sierra significantly broadened its scope beyond traditional marine engine parts to encompass a wider range of boating accessories and even outdoor power equipment components. This strategic expansion brought established marine brands like Shields and Moeller under the Sierra umbrella, creating a one-stop resource for marine maintenance and replacement parts. The company now offers fuel systems, electrical components, battery charging solutions, and NMEA electronics alongside their traditional engine parts lineup.</p><h3>Quality Backed by Industry-Leading Warranties</h3><p>What sets Sierra apart in the crowded aftermarket marine parts market is their commitment to standing behind every component they manufacture. Their warranty coverage extends beyond simple part replacement—it includes shop labor, haul-out fees, towing charges, and related incidental costs should a warrantied part fail. This comprehensive protection reflects the company's confidence in their manufacturing processes and quality control standards. For boat owners facing repairs far from shore or mechanics working on customer vessels, this peace of mind is invaluable. Whether you're maintaining an outboard motor, rebuilding an inboard engine, or upgrading your boat's instrumentation, Sierra's decades of marine industry experience and commitment to quality make them a reliable choice for keeping your vessel running at peak performance.</p>

Part Number

18-1908K
06/01/2036 3:49 AM
Sale Price

$376.96

In Stock (10+)

delivery box

Usually delivered within 2 days

free shipping

FREE SHIPPING

Authorize Seller Badge
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

Great experience...price was unbeatable and customer service was very responsive.

fast service and fair price

purchased two shocks for my truck, best price online , they were here within a week. I will definitely order from them again....thanks....

Quick and convenient.

Quick easy order

Easy to use website, great prices!

It was helpful and I could navigate easy . Good parts , crazy shipping prices but it's german cars and I got it fast so no complaints here.

good

unable to find MEGUIARS#40vinyl/rubber cleaner 16oz. locally autoplicity had it on line in stock at a great price. fast shipping,great comm.with buyer.will buy from them again thank you.

thanks

I don't typically review online stores, but Autoplicity was awesome! Shipped ridiculously quickly and my H&R springs were at my house two days after I ordered. Awesome, and for a great price. Thanks guys

Return customer with a few more future purchases in mind...best price plus quick shipping means these guys are just that good!

Share icon
Return Policy
Returns are easy at Boatplicity

Not happy with a purchase? No problem. We've made returning items as easy as possible. And most purchases can be returned for free for 30 days. Learn more about our Returns Policy