Xtreme Performance - Holley Ultra XP™ Circle Track Carburetors

Introducing the Holley Ultra XP™ Circle Track Carburetor, a fantastic choice for any racing enthusiast! These carburetors are designed to be up to 38% lighter than our traditional race models, making them a breeze to handle. With a fuel capacity that’s 20% greater, you can count on them to keep your engine running smoothly, even during those intense races. And that's not all—these carburetors come packed with 30 new features to enhance your racing experience!

Available in a sleek Hard Core Gray™ hard coat anodized finish with Black™ billet components for superior corrosion protection, you can also opt for the natural tumble-polished aluminum version, which features Black™ metering blocks and base plates. The Aluminum Ultra XP Circle Track carbs come in both 650 and 750 CFM options, specifically calibrated for circle track racing.

Among the standout features are an anti-siphon valve in the main body, high-capacity fuel bowls that provide 20% more fuel capacity to prevent starvation, and an integrated fuel shelf that minimizes aeration. Internal baffling also helps control fuel slosh, ensuring your performance stays consistent. The entire construction is made from aluminum, making it both lightweight and durable.

These carburetors include fully tunable billet metering blocks, a billet base plate, wedge floats, adjustable secondary linkage, and knurled curb idle screws that are easy to adjust by hand. Holley Ultra XP carburetors truly represent the pinnacle of square bore race carburetors!

Important Downloads:

• Instructions for Part# 0-80812BKX

Features:

• Aluminum construction that saves 4.5 lbs—38% weight savings!
• Stylish black anodized billet aluminum metering blocks and base plate
• Calibrated specifically for circle track use
• Set screw in the base plate for wide open throttle stop adjustment
• PTFE coated throttle shafts ride in oil-impregnated bronze bushings for smooth operation
• Anti-siphon valve in the main body to reduce pump pullover
• Contoured venturi inlet for balanced airflow and increased horsepower
• Air bleeds are positioned outward for a smoother airflow transition
• Durable metering blocks with true gasket sealing and fully adjustable features
• Integrated idle bypass valve for easy idle adjustments without throttle plate holes
• Dual 30cc accelerator pumps for the perfect fuel delivery from idle to full throttle
• Fuel bowls with 20% more capacity and internal baffling to control slosh
• Clear sight windows on both sides of the bowls for safe fuel level adjustments
• Convenient drain plug at the front center of the bowl for easy access
• -8 (o-ringed) inlet threads compatible with various plumbing options
• Four corner idle adjustment for precise control
• Tunable bleed off in the internal pump passage for further accelerator pump tuning
• Knurled primary and secondary curb idle screws for tool-free adjustments
• Primary throttle shaft capped to keep out debris and contaminants
• Factory machined accessory mounting hole for easy throttle stop addition
• Set up with 1:1 throttle actuation
• Baseplate designed with a boss for vacuum source machining
• Equipped with wedge floats
• 100% wet-flow tested to ensure it’s ready to perform right out of the box!

Specifications:

• Barrels: 4
• Billet Color: Shiny with Black Billet
• Booster: Down Leg
• CFM: 650
• Choke: None
• Circuit: 2
• Emission Code: 3
• Finish: Shiny
• Fuel: Gasoline
• Fuel Inlet: Dual
• Material: Aluminum
• Model: 4150
• Primary Main Jet: 74
• Primary Power Valve: 6.5
• Primary Pump Nozzle Size: 32
• Product Type: Ultra XP Carburetor
• Secondaries: Mechanical
• Secondary Main Jet: 82
• Secondary Pump Nozzle Size: 32
• Supercharged Application: No
• Throttle Bore: 1.688 inch
• Venturi Size: 1.250 inch
• Warranty: Limited 90 Day

Notes:

• This carburetor features a square bore flange bolt pattern, making it compatible with Holley, Edelbrock, Carter AFB, and Autolite style carburetors that have a 5 3/16" x 5 5/8" bolt pattern. If you have a spreadbore intake manifold, you’ll need an adapter, like the Mr. Gasket #1932, to install this carburetor.