Generic 650 CFM 4-Barrel Carburetor — BR-67255 4150 Flange, Mechanical Secondary & Electric Choke

BR-67255 is a 650 CFM, 4-barrel performance carburetor built on the 4150 square-bore flange pattern, featuring a mechanical secondary and electric choke for reliable throttle response and easier starting.

This carburetor is engineered as a direct-fit, high-flow replacement for applications that use Holley-style 4150 flange patterns. Constructed from lightweight die-cast aluminum with a polished finish, it combines durability with lower operating temperatures and reduced distortion under heat. The unit arrives ready to run with minimal tuning required—typical adjustments are idle and air/fuel mixture—and is optimized for street and performance builds where crisp throttle reaction is important.

How does the mechanical secondary affect throttle response?

The mechanical secondary uses a direct linkage that opens the secondary barrels progressively with throttle movement, delivering immediate power when you demand it. Compared with vacuum secondaries, this setup gives firmer, more predictable acceleration—beneficial for spirited driving and performance applications.

• Immediate secondary opening under throttle for stronger acceleration
• Consistent pedal feel across RPM ranges
• Better suited to throttle-focused driving and racing-style launches

Will this unit bolt onto my existing Holley 4150 manifold?

Yes—BR-67255 is designed around the 4150 square-bore flange pattern to match manifolds and intake runners that use that specification. Ensure your manifold and throttle linkage geometry match the 4150 layout before installation.

• 4150 square-bore flange pattern for direct compatibility
• Mechanical secondary throttle uses conventional linkage mounting points
• Check clearances for electric choke wiring and mounting brackets

What makes this carburetor reliable for daily driving and high-performance use?

The die-cast aluminum body reduces weight and dissipates heat more effectively than heavier materials, which helps keep parts stable under load. The polished surface resists corrosion and eases cleaning, while factory-calibrated circuits allow the carburetor to operate well out of the box with only routine tuning.

• Lightweight alloy construction minimizes warpage from heat
• Polished finish for durability and simplified maintenance
• Pre-set calibrations require only idle and mixture tuning for initial setup

How do the electric choke and user adjustments simplify startup?

The electric choke lets the carburetor manage cold starts using engine-side power rather than vacuum signals, so choke operation is more consistent across installs. After initial idle and air/fuel adjustments, most users find starting and warm-up behavior to be straightforward.

• Electric choke for predictable cold-start behavior
• Simple idle and air/fuel screws for quick tuning
• Factory assembly reduces the need for extensive jetting changes in many setups

Who this is for: BR-67255 is aimed at enthusiasts and mechanics who need a 650 CFM, four-barrel replacement that fits Holley 4150-style manifolds and delivers robust throttle response. It suits street performance cars, mild race builds, and restoration projects where modern materials and straightforward tuning are priorities. If you require a vacuum-secondary setup or specific OEM tuning, confirm requirements before purchase—otherwise, this carburetor is a practical, durable option for improving throttle feel and engine responsiveness.