Holley Ultra HP Carburetors

What's new about the latest release from Holley?

Holley’s new racer-inspired Ultra HP line of carburetors leverages the latest trends and technologies learned on the track – from reducing weight to redesigning the bowl for increased capacity and fuel control. In fact, Holley added 30 new features not found on the previous generation HP models to help engine builders take advantage of improved cylinder heads and more aggressive camshaft profiles.

“Engines continue to get bigger and make more power and race fuels continue to evolve, leading us to more testing and calibration of our carburetors with the current race fuels. With all of these changes, there was a need to provide the additional air and fuel curves to match,” explains Holley’s Bill Tichenor. 

Custom Carb Features

It has 30 new features over the traditional HP and racers are more savvy than ever on how to use them. – Bill Tichenor

The Ultra HP is not simply an old 4150 HP carburetor with a couple of new features and a new name to market it with. This is a radical, new design of what has been the go-to carburetor for many racers and enthusiasts for years. According to Tichenor, “It has 30 new features over the traditional HP and racers are more savvy than ever on how to use them.”

To start, 97% of the parts in this carburetor are aluminum. It is 38% lighter than it’s predecessor (about 4 1/2 pounds), and while that does not equate to a large amount of weight, every bit is important in drag racing.

Metering Blocks And Fuel Bowls

The Ultra HP utilizes billet metering blocks for improved durability and sealing, These blocks also incorporate an integrated pry port for easier disassembly. The fuel bowls have 20% more capacity than those on the standard HP carburetor, greatly reducing the risk of fuel starvation and stabilizing air fuel ratios.

There’s also internal baffling in the bowls to reduce fuel slosh under hard g-loads — whether they come from starting line launches at the drag strip or hard cornering in a road course car. There is a fuel shelf below the needle and seat to minimize aeration, and a fuel trough has been built into the bottom of the bowl to route fuel directly to the jets to keep them covered — again allowing for more stable air fuel ratios. 

The no-nonsense throttle lever eliminates provisions not needed on hardcore street or race cars, making swaps faster and allowing for tighter space constraints. The linkage mounting point is slightly different than what you would find on a traditional 4150, which required us to make a small adapter bracket.

Base Plate And Throttle Linkage

Outside the carburetor there are several features that racers and hardcore enthusiasts alike will appreciate. The base plate is made from 6061 aluminum to allow for better gasket sealing and a true surface. It also features elongated dual pattern mounting holes, allowing the Ultra HP to be mounted on either a standard square flange intake, or a Dominator flanged intake, further expanding it’s versatility. The throttle lever has been designed as race-only, with all of it’s unnecessary attachment points and tangs removed, further simplifying installation while removing unnecessary weight and clutter. 

Other Features

Fuel inlets can be plumbed from either side and come standard with a -8AN o-ringed inlet size. A -6AN male adapter is also included to further expand fuel line options. The primary and secondary curb idle screws have been knurled to allow for tool-free adjustment by hand. The secondary linkage is stainless steel and can be adjusted for progressive or 1:1 activation.

The integrated idle bypass valve helps maintain idle quality even with very radical camshafts and is perhaps one of the most user friendly innovations on this carburetor. The airbleeds have been moved outwards to allow for smoother transition of airflow. Even the squirter screws have contoured hex heads to help improve airflow as it enters the carburetor. 

Color choices available include black, polished, and a new Hard Core gray. The finish on these carburetors is hard anodized which should allow for years of easy cleaning and corrosion resistance. 


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