850 CFM - 4150 - Mechanical Secondaries - Shiny - Gasoline

Part Number: 0-80804BKX

Xtreme Performance - Holley Ultra XP™ carburetors! Ultra XP carbs are up to 38% lighter than our traditional race carbs, have fuel capacity that is 20% greater and 30 other new features! They're available in our all-new Hard Core Gray™ hard coat anodized finish with Black™ billet for improved corrosion protection. They're also available in natural tumble-polished aluminum with your choice of Black™ or Red™ metering blocks and base plate. The Aluminum Ultra XP comes in 600, 650, 750, 850, and True 950-CFM. Holley Ultra XP carburetors offer new features such as an integrated idle bypass valve that allows for idle adjustments while maintaining the correct throttle plate to transfer slot relationship, high capacity fuel bowls which feature 20% more fuel capacity to eliminate starvation, integrated fuel shelf to minimize fuel aeration and internal baffling to control fuel slosh. Other features include all aluminum construction, fully tunable billet metering blocks, billet base plate, adjustable secondary linkage and knurled (hand adjustable) curb idle screws. Holley Ultra XP carburetors are the ultimate in square bore race carburetors!

Features and Benefits

• Aluminum Construction (saves 4.5 lbs - 38% weight savings)
• Shiny with black anodized billet aluminum metering blocks and base plate
• Designed for use on Drag race, circle track, or any high horsepower engines
• Contoured venturri inlet offers balanced airflow for increased horsepower
• Air bleeds moved outward to allow a smoother transition of airflow from the top of the carburetor into the venturii
• Metering blocks feature improved durability, true gasket sealing and fully adjustable (emulsion bleeds, power valve channel restrictors & idle feed restrictors)
• Integrated idle bypass valve eliminates the need for holes in throttle plates and allows for proper adjustment of idle while maintaining correct throttle plate to transfer slot relationship.
• Helps maintain good idle control when using radical camshafts.
• Dual 30cc accelerator pumps provide the perfect amount of fuel from idle to full throttle
• Fuel bowls provide 20% more fuel capacity while controlling slosh with internal baffling
• Clear sight windows on both sides of bowls for easy and safe fuel level adjustments
• Built in drain plug in front center of bowl provides easy access to empty contents of bowl
• 8AN (o-ringed) inlet threads offer a large variety of plumbing options and can be plumbed from either side
• 4 corner idle allows you to precisely control your idle system
• Mechanical Secondaries for perfect off the line launches
• Elongated (dual pattern) mounting holes allow fitment on intakes with square flange (Holley 4150™ style) or large flange (Holley Dominator® style)
• Knurled (hand adjustable) primary and secondary curb idle screws allow for easy idle adjustment without the use of tools
• Primary throttle shaft capped to prevent entry of debris & contaminates
• Factory machined accessory mounting hole for easy addition of adjustable primary throttle stop. New secondary pump cam lever designed to provide positive throttle stop on secondary side
• Stainless steel adjustable secondary link. Provides choice of 1:1 or progressivesecondary throttle actuation for ultimate control of secondary opening rate
• Baseplate designed with a boss that can be consumer machined for vacuum source
• Includes notched float and jet extensions
• 100% wet-flow tested by Holley technicians to assure it arrives ready to run!

This carburetor was designed with a dual mounting pattern, so that it can be installed on a manifold machined for a 4150 or 4500 series carburetor.