Speedmaster 1-147-023 Features:

Step up to the high-rpm power of an open plenum with Speedmaster HiRise intake manifolds. These cast aluminum manifolds accept square-bore carburetors and are pressure tested to ensure maximum performance. They start to make awesome power around 3,000 rpm. These Speedmaster HiRise manifolds for Big Block Chevys are a worthy companion to our phenomenally successful single plane small block racing manifold. Designed for serious performance big block applications, they feature nitrous bosses, dual distributor holddowns, four corner water ports, and are available for both rectangular or oval port cylinder heads. Rectangular port size at the gasket flange is 1.69-inches wide by 2.31-inches tall, which can be opened up to match the gasket and/or larger port cylinder heads. Runner size is effective for 468 to 540 cid engines. Note: Use Fel-Pro intake gaskets #1211 (Printoseal) or #1275 (non-Printoseal). Both of these gaskets are the standard 1/16-inch thickness. Fel-Pro also offers a 1/8-inch thick non-Printoseal gasket set #1239 which could be required in some instances where the cylinder heads have been machined. Use an 800 cfm or larger 4150 square bore carburetor.

• Step up to the high-rpm power of an open plenum
• Design for racing applications or for serious street performance
• Cast from steel molds for a tighter grain and reduction of porosity
• Pressure tested to ensure maximum performance

  Emissions Note:

  This part is only legal for sale and use on Uncontrolled (Non-Emissions Controlled) Vehicles or on vehicles used solely for the purposes of closed competition racing.

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