Generic 650 CFM 4-Barrel Carburetor BR-67255 — 4150 Flange, Mechanical Secondary, Polished

The BR-67255 is a 650 CFM 4-barrel replacement carburetor built to the 4150 square-bore flange pattern, offering mechanical secondary throttle response and an electric choke for reliable street and performance use.

This direct-fit, high-flow carburetor is engineered to be compatible with Holley-style manifolds and setups while delivering strong throttle response, simplified tuning, and durable construction. Finished in polished die-cast aluminum, the BR-67255 combines a 650 CFM airflow rating with a mechanical secondary design and electric choke to suit many V8 street and performance applications. Below you’ll find quick answers to common buyer questions plus clear, actionable specs to help you confirm fitment and features.

Will this carburetor fit my engine and manifold?

The BR-67255 uses a 4150 square-bore flange pattern, making it compatible with most intake manifolds designed for Holley-style 4-barrel carbs. Check your intake flange bolt pattern, throttle linkage style, and fuel inlet orientation to ensure a smooth installation. Carburetor studs and gaskets are typically the same as other 4150-pattern units.

• Flange: 4150 square-bore bolt pattern
• CFM: 650, suitable for many small- to mid-displacement V8s
• Throttle: Mechanical secondary for positive response
• Choke: Electric choke for easier cold starts

How does the mechanical secondary affect performance?

A mechanical secondary uses a direct linkage to open the secondary barrels based on throttle input rather than engine vacuum, which produces crisper throttle response and more predictable progression under load. That makes the BR-67255 especially useful for spirited street driving and performance builds where immediate power delivery is desired. It also simplifies tuning compared with some progressive vacuum-secondary designs.

• Quicker secondary opening for immediate acceleration
• More consistent progression at wide-open throttle
• Better suitability for performance camshafts and headers

What materials and build quality can I expect?

This carburetor is manufactured from lightweight die-cast aluminum to reduce thermal distortion and overall weight while providing durable service life. The polished exterior improves corrosion resistance and appearance under the hood. Internal machining and factory calibration aim to deliver reliable out-of-the-box operation with minor idle and air/fuel adjustments.

• Body: die-cast aluminum for lower heat soak and less warpage
• Finish: polished surface for longevity and aesthetics
• Pre-adjustment: factory-set; requires idle and mixture tuning

How easy is it to install and tune this carburetor?

The BR-67255 arrives pre-assembled and typically needs only basic idle and air/fuel adjustments to run properly. It uses standard Holley-style linkage and fuel inlet fittings so most installations follow conventional 4150-pattern procedures. If you’re swapping from another 4150 carb, installation time is often minimal; new users should have basic tools and a manual for fine-tuning.

• Out of box: runs after minor idle and mixture adjustments
• Linkage: compatible with standard 4150 throttle setups
• Tuning: adjust idle speed and air/fuel screws for best results

Who is this for: The BR-67255 650 CFM 4-barrel carburetor is aimed at street performance enthusiasts, classic car restorers, and engine builders looking for a reliable Holley-pattern replacement with responsive mechanical secondaries and an electric choke for easier starts. It suits small- to mid-displacement V8 engines and builds where throttle response, durability, and straightforward tuning are priorities rather than complex electronic control. Verify flange compatibility and fuel system configuration before purchase to ensure a plug-and-play swap for your application.