650-850 CFM Primary Metering Block

The 650-850 CFM Primary Metering Block from Advanced Engine Design is a precision aluminum fuel regulation component engineered for high-performance Holley 4150 carburetors. Built for engine builders, carburetor tuners, and performance enthusiasts, this metering block controls fuel delivery to the primary circuit under cruise and part-throttle conditions. Whether you're dialing in a street engine, bracket racer, or restored classic, accurate primary metering is essential for drivability, fuel economy, and reliable power delivery across the RPM range.

Machined from aluminum and finished with chromate coating for corrosion resistance, the 650-850 CFM Primary Metering Block delivers consistent fuel atomization through precisely calibrated jets and ports. The chromate finish protects against oxidation in high-heat engine bay environments while maintaining dimensional stability. This block regulates main jet sizing and fuel distribution to match airflow through the 650–850 CFM flow range, allowing tuners to match fuel supply to air demand and prevent lean stumbles or rich hesitation. Compact dimensions (3.65 × 1.85 × 5.35 inches) and lightweight construction (0.89 lbs) integrate seamlessly into existing Holley 4150 carburetor mounting without modification.

Ideal for street rods, truck restorations, drag racing platforms, and street/strip dual-purpose builds, this metering block suits anyone upgrading or replacing worn carburetor internals. Installation requires standard carburetor gasket removal and bolt replacement—no special tools needed. Compatible exclusively with Holley 4150 series carburetors, this block ensures OEM-equivalent flow characteristics and tuning precision for engines ranging from 350 to 500+ cubic inches, making it a trusted choice among professional engine shops and serious gearheads seeking repeatable, bolt-on fuel metering performance.