RoyalAir 1/4in Phenolic Carburetor Spacer for Holley 4150/4160 & Edelbrock — 4-Hole Thermal Insulator, Improved Throttle Response

RoyalAir's 1/4-inch phenolic carburetor spacer is a four-hole thermal barrier engineered to fit Holley 4150/4160 and Edelbrock carbs, improving throttle response and helping keep fuel temperatures cooler.

This precision-machined spacer sits between the carburetor and intake manifold to reduce heat transfer from the engine, help stabilize air-fuel mixture distribution, and provide a secure mounting interface. Constructed from high-grade phenolic material, it resists heat flow better than many metals while remaining rigid enough for reliable, repeatable sealing. The part is a direct replacement for Canton Racing 85-154 and is drilled with four mounting holes to align with common 4150/4160 bolt patterns.

How does this spacer change throttle response and mixture distribution?

By adding a short, 1/4-inch gap between the carb and intake, the spacer creates a small plenum that evens out fuel atomization across the four corners of the intake. That improved distribution reduces uneven cylinder fueling at part-throttle and under load, which often translates to sharper throttle response and smoother transitions.

• 1/4" thickness smooths flow and shortens the path for fuel/air mixing
• Four precisely machined holes align with 4150/4160 bolt patterns for balanced flow
• Phenolic surface minimizes heat soak into the carburetor base

Will this spacer help prevent vapor lock in hot conditions?

The phenolic material acts as a thermal insulator, reducing direct heat transfer from the intake manifold into the carburetor fuel bowls and metering block. While no component can guarantee elimination of vapor lock under every extreme condition, reducing heat soak lowers the risk and helps maintain cooler, more consistent fuel temperatures.

• Phenolic construction reduces conduction compared with metal spacers
• Maintains a cooler carburetor base temperature under sustained load
• Helps stabilize fuel vapor pressure near the metering circuits

Is the RoyalAir spacer easy to install and compatible with my carburetor?

Yes — the spacer is drilled and countersunk to match standard Holley 4150/4160 and common Edelbrock performer bolt patterns, making it a drop-in solution for most setups that use those carburetor families. Installation uses standard mounting hardware; make sure to use a proper gasket and torque bolts evenly to prevent air leaks.

• Designed for Holley 4150/4160 series and Edelbrock performer carbs
• Four corner mounting holes for secure attachment and correct sealing
• Direct replacement for Canton Racing 85-154 model

What material and dimensions should I expect from this part?

The spacer is manufactured from durable phenolic for low thermal conductivity and reliable mechanical strength. Its nominal thickness is 1/4 inch and the center and bolt openings are CNC-machined for consistent fitment with matched carburetor and manifold surfaces.

• Material: high-grade phenolic for thermal isolation
• Thickness: 1/4 inch with four precision-cut passages
• Finish: machined openings and mounting holes for accurate alignment

Who is this for? The RoyalAir 1/4" carburetor spacer is aimed at automotive enthusiasts, restorers, and mechanics who run Holley 4150/4160 or compatible Edelbrock carbs and want an easy, reliable way to reduce heat transfer, improve mixture distribution, and sharpen throttle response. It suits street-driven V8s, mild to moderately tuned performance engines, and anyone seeking a direct, OEM-style replacement for Canton Racing 85-154 without altering jetting or carb calibration. As with any intake modification, use appropriate gaskets and follow torque specifications during installation.