18-1908 3" Spacer for Center Riser

Increase riser height for hose clearance or put exhaust outlets further above the waterline

3" can make a big difference in combatting back-flow issues on engines installed close to the transon or waterline. These Sierra spacers provide the extra height to prevent water from traveling back into the riser when throttling down and  can also provide added clearance for exhaust hose routing. Engineered to be compatible with many GM based V-6, small block and big block engines.

For 50 years Sierra has been producing parts engineered to meet or exceed the specifications of marine engine manufacturers and has gained the confidence of engine manufacturers and boat builders to a point of supplying them with OEM parts. Boaters and technicians can be assured a Sierra part will fit right the first time and restore function to manufacturers' standards.

Key Features

• Engineered to meet or exceed OEM specifications
• Adds 3" of height to exhaust riser to prevent back-flow issues or add exhaust hose clearance
• Compatible with manifolds used on 229 and 262 cu. in V6 and 305-350 cu. in. Small Block V8 and 454 cu. in Big Block V8 engines
• Requires one ea: 18-0897, 18-0672, and 18-2849-1 gaskets
• For a complete kit with two spacers, gaskets, bolts and plugs use Sierra p/n 18-1908K
• Backed by SeaStar Solutions Limited Two-Year Warranty

The Sierra Engine Parts Selector

In addition to risers, we offer a wide variety of other engine parts manufactured by Sierra. To see if we have the part you need, see our Engine Parts Selector, where you can search by engine make, serial number and model or year of manufacture.