SHLPDFM Carburetor Spacer 1in Black Phenolic Open for Holley 4150/4160 — Adds Plenum Volume, Reduces Heat Transfer

SHLPDFM 1" black phenolic open carburetor spacer fits Holley 4150/4160-style 4-barrel carbs to add plenum volume and reduce heat transfer between the intake and carburetor. This 1" open spacer is molded from phenolic resin and designed for square-bore 4-barrel carburetors such as Holley 4150/4160, Barry Grant, Carter and Edelbrock. It ships with two gaskets and mounting hardware so it’s ready to install on many small- and big-block Chevy, Ford and Chrysler Mopar applications. The spacer’s open center increases plenum volume for high-rpm breathing while the phenolic material helps insulate the carburetor from manifold heat.

How does a 1" phenolic spacer affect carburetor heat and fuel mixture?

The phenolic material has lower thermal conductivity than aluminum, which slows heat flow from the intake manifold into the carburetor base. That helps keep the fuel charge cooler and denser under many operating conditions.

• Phenolic construction reduces heat soak compared with metal spacers.
• Cooler carburetor base can help maintain more consistent air/fuel density.
• Less heat transfer reduces vaporization at the carburetor venturi and bowls.

Will this spacer fit my Holley 4150/4160 or similar 4-barrel carb?

Yes — it is built for square-bore 4-barrel carburetors with the Holley-style bolt pattern and flange dimensions. It’s compatible with many aftermarket carbs sharing that square flange layout.

• Fits Holley 4150 and 4160 flange patterns directly.
• Works with Barry Grant, Carter and Edelbrock square-bore carbs that match the pattern.
• Suitable for many SBC, BBC and big-block Ford and Mopar intake manifolds with matching flange spacing.

What performance changes should I expect from the open 1" design?

The spacer’s open center increases plenum volume and changes the airflow path into the carburetor. That generally favors improved high-rpm airflow, while the open layout tends to preserve mid- and top-end power characteristics.

• Open design increases plenum volume for higher-rpm breathing.
• Helps fine-tune midrange response depending on carb and camshaft setup.
• May require minor jetting or tuning adjustments after installation.

What comes in the box and how is the spacer installed?

The product ships complete with mounting hardware and two gaskets. Installation is straightforward for anyone familiar with carburetor removal and mounting — tighten to proper torque and follow gasket sealing best practices.

• Includes one 1" black phenolic spacer, two gaskets and mounting bolts.
• Install between intake manifold and carburetor using supplied gaskets.
• Torque bolts evenly to manufacturer torque specs to avoid warpage.

This spacer is ideal for engine builders, restorers and performance enthusiasts looking to tune inlet characteristics without permanent manifold modification. It’s best suited to street/strip and track builds using square-bore 4-barrel carburetors where added plenum volume and reduced heat transfer are desired. Avoid using this spacer on carburetors or manifolds that do not share the Holley-style bolt pattern or square-bore flange; confirm fitment before installation to ensure compatibility and safe operation.

FAQ

Q: Does this spacer fit Holley 4150 and 4160 carbs?

A: Yes. It fits square-bore Holley 4150/4160 flange patterns and similar square-bore 4-barrel carbs.

Q: Will I need new jets after installing the spacer?

A: Not always. Some setups require minor jetting or tuning adjustments depending on cam, intake and engine state of tune.