It may be the most widely-used-and most recognizable-name in racing, but Holley isn't resting on its laurels. In an effort to reduce the need for expensive carb tuners and provide racers with an even better carburetor right out of the box, Holley has introduced its new lineup of Ultra Series carbs.
Holley's new Ultra Series carburetors feature billet metering blocks and base plates as we
These four-barrel carburetors are available in 650, 750 and 950 cfm versions and are based on the venerable 4150 HP Series that has been raced for years. What separates the Ultra line is the addition of billet metering blocks and base plates versus the standard cast units.
Holley's engineers say that the design of the billet metering blocks not only provides more accuracy and durability, but also allows more control over the fuel curve. Emulsion jet changes make for more control and better repeatability. Idle feed restrictors are also included so that no drilling is required. The power-valve restrictors are also changeable.
Along with the metering blocks, Holley has switched out the baseplate for one of machined aluminum. Most experienced racers know that the "ears" on the cast baseplate are a bit fragile, and too much torque when bolting the carburetor to the intake manifold or spacer can cause the casting to crack. But it still happens too often when making last-minute changes and trying to get the carburetor installed before the heat races start. The billet baseplate should cure that problem.
Other options are all about providing additional tuneability. They include oversized sight windows in the bowls for easier float adjustments and replaceable air bleeds in the two circuit metering system. Ultra Series carbs are also equipped with 30cc accelerator pumps, progressive mechanical secondaries, non-stick gaskets, a notched secondary float with jet extensions, power-valve blowout protection and down leg boosters.
Currently, the Ultra Series of carbs are so new that they may not be legal in rulebooks that specify specific Holley part numbers. But in racing classes with more open carburetor rules, this may be just the ticket. As Holley insiders say, the Ultra Carbs should help you get closer to the quality of a custom-tuned carburetor at a fraction of the cost.
Holley Performance Products
1801 Russellville Rd.
Bowling Green, KY 42101