Sierra 18-1908 Manifold Riser Spacer, 3 Inch, OEM 933220A12, Fits Mercruiser Manifold 18-1953-2

The Sierra 18-1908 is a 3 inch manifold riser spacer engineered to fit Mercruiser exhaust manifold 18-1953-2. It is built from aluminum and is primed and painted for added durability and corrosion protection, arriving ready to install out of the box. The spacer sits between the exhaust manifold and the riser elbow, and it is designed to be used with a specific mounting kit depending on which elbow and riser combination is installed: pair it with mounting kit 18-8554 when using riser 18-1970-2, or with mounting kit 18-8555 when using riser 18-1976-2. It carries the OEM cross-reference number 933220A12, so it is a direct equivalent for that original part.

This spacer is intended for engine setups that pair with manifold 18-1953-2, including Mercruiser GM Big Block V8 454 cid engines (Models 330, 340 & 74L), GM Small Block V8 305-350 cid engines (Models 200, 228, 230, 260 & 898), and GM V6 229 & 262 cid engines (Models 185 & 205). When sealing the elbow to this spacer, elbow gasket 18-0672 is the compatible closed-style gasket for this fitment. Note that mounting the elbow to the spacer requires its own separate mounting kit rather than reusing the elbow's original hardware.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-1908
• Product Type: Manifold Riser Spacer
• OEM Cross Reference: 933220A12
• Spacer Height: 3 inches
• Material: Aluminum
• Finish: Primed and painted
• Auto Part Position: Front
• Weight: 6.32 pounds
• Package Dimensions: 5.25 inches L x 5.75 inches W x 5.5 inches H
• UPC: 808282127503
• Fits Manifold: 18-1953-2
• Compatible Mounting Kits: 18-8554 (with riser 18-1970-2), or 18-8555 (with riser 18-1976-2)
• Compatible Elbow Gasket: 18-0672

Fitment

• Mercruiser GM Big Block V8 454 cid (Models 330, 340 & 74L)
• Mercruiser GM Small Block V8 305-350 cid (Models 200, 228, 230, 260 & 898)
• Mercruiser GM V6 229 & 262 cid (Models 185 & 205)
• Fits manifold 18-1953-2

Replaces (OEM)

• 933220A12

Frequently Asked Questions

What engines does the Sierra 18-1908 manifold spacer fit? The Sierra 18-1908 fits manifold 18-1953-2 and is used on Mercruiser GM Big Block V8 454 cid engines (Models 330, 340 & 74L), GM Small Block V8 305-350 cid engines (Models 200, 228, 230, 260 & 898), and GM V6 229 & 262 cid engines (Models 185 & 205).

Is 18-1908 the same as OEM part 933220A12? Yes, Sierra 18-1908 carries OEM cross-reference number 933220A12, making it a direct equivalent for that original manifold spacer.

How thick is this manifold spacer? The Sierra 18-1908 is a 3 inch spacer designed for manifold 18-1953-2.

What material is the 18-1908 spacer made from? It is made from aluminum and is primed and painted for added durability and corrosion protection.

Does the 18-1908 spacer come pre-painted or does it need to be finished after installation? The Sierra 18-1908 arrives primed and painted from the factory, so it is ready to install out of the box without additional finishing.

Which mounting kit do I need with the 18-1908 spacer? It depends on the riser installed: use mounting kit 18-8554 with riser 18-1970-2, or mounting kit 18-8555 with riser 18-1976-2, alongside the 18-1908 spacer.

What gasket do I need to seal the elbow to the 18-1908 spacer? Elbow gasket 18-0672 is the closed-style gasket that fits the 18-1908 spacer along with manifold 18-1953-2.

How much does the 18-1908 manifold spacer weigh? The Sierra 18-1908 weighs 6.32 pounds.

What are the package dimensions of the 18-1908 spacer? It ships in a package measuring 5.25 inches long by 5.75 inches wide by 5.5 inches high.

Can I mount the elbow directly to the 18-1908 spacer using the elbow's original hardware? No, mounting an elbow to the 18-1908 spacer requires its own separate mounting kit rather than reusing the elbow's original mounting hardware.

What is the difference between the 18-1908 and the 18-1985 spacer? The 18-1908 is a 3 inch spacer for manifold 18-1953-2, while 18-1985 is a 6 inch spacer for the same manifold and requires its own separate mounting kit (18-8556).

Is the Sierra 18-1908 a genuine Sierra part or a generic aftermarket copy? The 18-1908 is a genuine Sierra International manifold riser spacer, manufactured as a direct equivalent to OEM part 933220A12.