Phenolic 1/2in Open

The Phenolic 1/2in Open carburetor spacer from MOROSO is a precision-engineered component designed for builders and tuners seeking to optimize induction cooling and manifold heat isolation on small-block and mid-sized engines. This spacer sits between the carburetor and intake manifold, creating critical airflow separation that reduces temperature transfer from the engine block to the fuel mixture—a fundamental advantage in high-performance and street applications where carburetor temperature stability directly impacts throttle response and fuel atomization consistency.

Constructed from phenolic resin, this material choice delivers excellent thermal insulation properties while maintaining structural rigidity under engine compartment heat and vibration. The 1/2-inch thickness provides an ideal balance between manifold clearance and insulation effectiveness, allowing for proper carburetor mounting while establishing the air gap needed to prevent heat soak in the fuel bowl. The open design—meaning no internal baffles or passageways—allows full exhaust heat crossover when required by your carb-to-manifold configuration, making it universally compatible with both divorced and integrated heat-riser systems. At just 0.47 lbs, phenolic spacers add negligible weight while delivering measurable improvements in fuel vaporization and cold-start characteristics.

Hot rodders, muscle car restorers, and carbureted engine builders rely on phenolic spacers as an economical first step in induction refinement, especially when working with Holley, Edelbrock, or OEM four-barrel carburetors on Chevy, Ford, and Mopar platforms. Installation requires only disconnection of the carburetor, removal of the original gaskets, positioning of the spacer with matching bolt holes, and reassembly—a 15-minute upgrade that yields noticeable improvements in throttle tip-in response and cruise-phase stability. Verify carburetor-to-hood clearance before installation on modified or lowered vehicles.