Xtreme Performance - Holley Ultra XP™ carburetors! Ultra XP carbs are 38% lighter than our original HP, 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!

Holley has been the undisputed leader in fuel systems for over 100 years. Holley carburetors powered every NASCAR Cup team and nearly every NHRA Pro-Stock champion for four decades. Now, Holley EFI products power these cars and are dominating the performance world. Holley products for GM's popular LS engine are dominating the LS scene as well. Holley's products also include performance fuel pumps, intake manifolds and engine dress-up products for street performance, race and marine applications. As a single solution or partnered with products from other Holley companies we can give you the edge you need over the competition!

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.

Hard Core Gray with black anodized billet aluminum metering block and booster inserts

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!

Product Description:

Carburetor

Model 4150

Ultra XP

4-Barrel

600 CFM

Square Bore

No Choke

Mechanical Secondary

Dual Inlet

Black Anodized

Sold Individually

For over a century Holley has driven the cutting edge of fuel-system design. That work continues today through Holley’s market-leading EFI products as well as through Holley’s family of best-in-industry brands. Top brands like MSD, Flowmaster, Hurst, Accel, and many more make up the industry’s leading offering of enthusiast-driven products to deliver robust, complete performance solutions for builders, racers, and drivers. From propelling the LS-, Coyote-, and Gen 3 Hemi-swap trends, to continuously innovating late-model and vintage vehicle performance, Holley’s commitment to its customers and their cars is at the core of everything we do.