
0-4412HBX Ultra XP 2-Barrel Carburetor 500 CFM
Holley 0-4412HBX Features:
The original Holley 0-4412 has powered thousands of racers to the winners' circle! How do you make it better? Add the proven design elements of the popular Ultra series for more tunability, more durability, more weight savings and more features! The Ultra XP 2bbl carburetors feature all aluminum construction for nearly 50% weight savings over their zinc counterparts, contoured venturii inlet for unobstructed airflow, screw in air bleeds for easy fine tuning, black anodized fully adjustable billet aluminum metering block and baseplate, high capacity fuel bowl which features 20% more fuel capacity to eliminate starvation, integrated fuel shelf to minimize fuel aeration and internal baffling to control fuel slosh and a centered air cleaner flange for improved airflow and performance. Other notable features include wedged floats, knurled hand adjustable curb idle screw and down leg boosters. Ultra XP 2bbl carburetors are approved for use in NASCAR® Mid-West/West Coast Late Model Divisions and utilize the same venturii and throttle bore dimensions of the classic 4412 2bbl carburetor. Available in shiny or Hard Core Gray finishes, the Ultra XP 2bbl will outperform any production 2bbl available.- All aluminum construction - for nearly 50% weight savings over zinc version
- Hard Core Gray with Black™ billet aluminum metering block and base plate
- No choke tower for unobstructed airflow
- Air bleeds moved outward to allow a smoother transition of airflow
- Air cleaner flange centered over venturii for improved airflow and performance. 5/16-18 bent air cleaner stud included
- Down-leg boosters for improved fuel signal
- Contoured hex head squirter screw for streamlined airflow
- Internal pump passage on metering block equipped with tunable bleed off
- Same 1-3/8” Venturii & 1-11/16” Throttle Bore size and Throttle Plate/Throttle Shaft size of original 0-4412
- Fuel bowl provides 20% more fuel capacity while controlling slosh with internal baffling
- Clear sight windows on both sides of bowl for easy & safe fuel level adjustments
- Fuel trough designed into floor of bowl to route fuel flow directly to the jets and assists in keeping jets covered by fuel
- Built in drain plug provides easy access to empty contents of bowl
- -8 (O-ring) inlet threads offer a large variety of plumbing options (come with an extended -8 O-ring to -8AN male adapter and -8 plug). Can be plumbed from either side
- Throttle shaft rides in oil impregnated sintered bronze bushings for smooth throttle actuation
- Throttle shaft capped to prevent entry of debris & contaminates
- 30cc pump with metal lever. Anti-siphon valve in mainbody to reduce pump pull over
- Dedicated race-only throttle lever with all unnecessary street attachment points & tangs removed
- Knurled (hand adjustable) curb idle screw allows for easy idle adjustment without the use of tools
- Set screw for wide open throttle stop adjustment
- Wedge float provides fuel control while cornering
- 100% wet-flow tested by Holley technicians to assure it arrives ready to run!
Emissions Note:
This part is only legal for sale and use on Uncontrolled (Non-Emissions Controlled) Vehicles or on vehicles used solely for the purposes of closed competition racing.
CLICK THIS LINK FOR IMPORTANT CARB & EPA EMISSIONS INFORMATION ABOUT THIS PART
The Holley Ultra XP 2-Barrel Carburetors are the first true Holley 2BBL carburetors designed and constructed specifically for racing applications. They're available in the stealthy appearing Hard Core Gray™ hard coat anodized finish or in natural tumble-polished aluminum with Black™ billet metering block and baseplate for improved corrosion protection. These carburetors are 500 CFM and will comply with the track inspection gages currently used to tech the venturi diameter, throttle bore and throttle-shaft/ butterfly thickness!
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6061-T6 Billet Aluminum Metering Block
- Improved durability, true gasket sealing (sealing surface integrity), hard coat anodized for good looks and superior corrosion protection
- Power valve channel restrictors now machined lower in metering block for improved fuel delivery to power valve circuit
- Accelerator pump channel now internally drilled eliminating need for external plug
- Excess material removed for improved fuel capacity
- Integrated pry-point assists in disassembly from fuel bowl and mainbody preventing damage to gaskets and gasket surfaces
- New snap in place bowl vent whistle makes removal and/or replacement easier
6061-T6 Billet Aluminum Base Plate - Improved durability, true gasket sealing, hard coat anodized for good looks and superior corrosion protection
- Dedicated race-only throttle lever with all unnecessary street attachment points & tangs removed
- Knurled (hand adjustable) curb idle screws allow for easy idle adjustment without the use of tools
- Throttle shaft capped to prevent entry of debris & contaminates
All-New Fuel Bowl Design - Completely redesigned from the ground up for racing
- 20% more fuel capacity vs. a traditional v-bowl eliminates fuel starvation and provides consistent air/fuel ratios
- Internal baffling to help control fuel slosh and minimize float level fluctuations in hard launching or cornering situations
- Fuel shelf below the needle and seat to greatly minimize fuel aeration and promote more consistent metering
- Fuel trough designed into floor of bowl to route fuel flow directly to the jets and assist in keeping jets covered by fuel
- Clear Pyrex® 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
- Contoured entry provides smooth fuel flow directly to needle & seat
- -8AN (o-ringed) inlet threads offer a large variety of plumbing options (come standard with -8AN o-ring to -6AN male adapter and -8AN plug). Can be plumbed from either side
- Material added in key areas (needle & seat area, fuel inlet, sight window area) for added strength in the demanding race environment
All-New 2BBL Racing Main Body - Air bleeds moved outward to allow a smoother transition of airflow from the top of the carburetor into the venturii
- Slash-cut vent tube
- Down-leg boosters for improved fuel signal
- No choke tower for unobstructed airflow
- All unnecessary mounting bosses removed for a smoother, cleaner appearance with a cast in Holley logo
- Contoured hex head squirter screws for streamlined airflow
- 1-3/8'' Venturii and 1-11/16'' Throttle bore size
- Track gages currently used to tech the venturi diameter, throttle bore and throttle-shaft/ butterfly thickness by race sanctioning bodies can still be utilized
Features:
- All aluminum construction - for nearly 50% weight savings over zinc version
- Available in Tumble polished aluminum or Hard Core Gray hard coat anodized with Black billet metering block and baseplate
- Hard coat anodizing on fuel bowls and mainbody - actually penetrates the aluminum for superior corrosion protection



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