Ultra XP C/T Carburetor 650CFM

The Ultra XP C/T Carburetor 650CFM from HOLLEY represents the modern standard for street and strip performance carburetors, engineered for builders seeking reliable fuel delivery across a broad RPM range. This 650 cubic feet per minute unit addresses a critical gap in the carburetor market: delivering consistent atomization and distribution without the tuning complexity of larger four-barrel designs. Whether you're building a classic muscle car restomod, a street rod, or a compact displacement engine, this platform delivers the air-fuel precision required for steady idle quality, responsive throttle response, and highway cruise efficiency.

The Ultra XP design incorporates HOLLEY's proven metering technology with dual-stage fuel bowls and secondary stage actuation calibrated for progressive opening under load. The 650 CFM rating places this carburetor ideally for small-block and mid-sized engines (typically 250–350 cubic inches) where oversized carburetors create off-idle hesitation and fuel economy loss. Cast aluminum construction weighing 9.6 lbs keeps induction system mass low while the compact 12.5 × 9.5 × 14.3 inch footprint simplifies manifold mounting and hood clearance on retrofit applications. Internal passages are optimized for velocity and mixing, reducing fuel ghosting in the transition circuits and ensuring clean throttle transitions even on carbureted fuel-injection conversion builds.

This carburetor is ideal for street enthusiasts, restoration shops, and performance tuners who prioritize reliability and driveability over maximum peak horsepower. The Ultra XP C/T works across a wide range of intake manifold designs, from single-plane street runners to dual-plane stock replacements, making it a versatile choice for bolt-on performance upgrades. Installation requires a four-barrel carburetor flange on your intake manifold; jetting and air-valve adjustments are straightforward and well-documented in the HOLLEY application guide. Cooling lines for the choke housing are included, and the carburetor supports both mechanical and electric choke configurations depending on your engine bay requirements and emissions posture.