ZLSCTT Carburetor Spacer 1" Ported Phenolic 4-Hole - Insulates and Improves Throttle Response

ZLSCTT's 1" ported phenolic carburetor spacer raises and insulates a 4‑hole square‑bore carburetor to improve throttle response and reduce heat soak.

This 1‑inch, four‑hole spacer is molded from phenolic resin to sit between your intake manifold and a 4150/4160 style 4‑barrel carburetor (compatible with common SBC and BBC setups). By adding distance and thermal isolation between the hot intake and the carburetor, the spacer helps preserve a cooler, denser air/fuel charge while providing a slight plenum effect that can improve midrange torque and throttle feel. The kit ships with two gaskets and four mounting studs and nuts to simplify installation on most square‑bore applications.

How does a 1" phenolic spacer affect engine temperature and fuel density?

The phenolic material has low thermal conductivity, which reduces heat transfer from the intake manifold into the carburetor. Cooler carburetor temperatures help the air/fuel mixture remain denser and less prone to vapor lock under heavy load or high under‑hood temperatures.

• 1" thickness provides measurable insulation between manifold and carburetor
• Phenolic resin resists heat transfer better than aluminum
• Denser charge can improve combustion consistency at cruise and part throttle

Will this spacer fit my 4150/4160 or square‑bore carburetor?

The spacer is a four‑hole ported design compatible with most 4150/4160‑style square‑bore carburetors and common SBC/BBC manifolds. It is intended for use with widely available brands and aftermarket 4‑barrel carbs that use the 4‑bolt flange pattern.

• Works with many Edelbrock, Barry Grant/Demon, and similar square‑bore carbs
• Designed for standard 4‑hole flange bolt patterns used on SBC and BBC engines
• Includes gaskets, studs and nuts for straightforward mounting

How does porting and the 4‑hole layout influence performance?

A ported 4‑hole spacer aligns with the four throttle bores to maintain airflow balance while adding a small plenum volume. This can smooth transitions between throttle openings and help midrange torque without drastically altering carb tuning.

• Ported openings match the carburetor bores to keep flow paths direct
• Added plenum effect can enhance throttle response and cylinder fill
• Maintains even distribution across all four bores for consistent performance

What comes in the box and what are the installation basics?

The package contains the 1" phenolic spacer, two matching gaskets, and four mounting studs with nuts to secure the assembly. Installation is a simple gasket‑and‑stud swap on most standard manifolds but always follow torque specs and check for vacuum/pressure leaks after assembly.

• Included: 1 spacer, 2 gaskets, 4 studs and nuts for secure fitting
• Install between intake manifold and carburetor using supplied gaskets
• Verify flange alignment, torque properly, and inspect for leaks

Who is this for? This ZLSCTT 1" 4‑hole phenolic spacer is aimed at street and weekend performance enthusiasts running square‑bore 4‑barrel carburetors on small‑block or big‑block Chevy, Ford, or Mopar applications who want reduced heat soak, improved midrange response, and an easy bolt‑on upgrade. It’s ideal if you need a compact spacer that preserves carb compatibility and includes all mounting hardware for a quick swap. Note: final tuning and jetting may be required after installation to optimize air/fuel ratios for your engine and driving conditions.