Holley Carburetors

General Carburetor Information
Which carburetor to choose? This question confronts anybody who is in the market for a carburetor, whether it is for the street, the drag strip or circle track.

offers a number of different carburetors that, looked at in total, may at first seem confusing. There is, however, a logical way to select the best carburetor for your particular needs. The obvious first place to start is with the application or vehicle on which the carburetor will be installed.

Sometimes there will be a choice of either a square flange or spread bore flange carburetor. Either style will work in such cases, but the square flange carburetor will require the purchase of an adaptor to bolt it on to a spread bore flange manifold, and vice versa.

A high performance street or street/strip application is the next scenario to consider. In this case we will have to reference the carburetor listing (by CFM) section of our catalog. The first thing to consider here is the CFM or amount of air flow that the engine will require.

There is a simple formula available that will put you right in the CFM ball park. The formula is: Engine Size (CID) x Maximum RPM/3456 = CFM @ 100% VE (Example: 350 CID x 6000 RPM = 2,100,000/3456 = 608 CFM) Approximately 608 CFM would be required for this engine.

However, most Street engines are capable of achieving only about 80% VE; a modified street engine with ported heads, headers, intake and carburetor can achieve about 85% VE; a fully modified race engine can achieve 95% VE. The CFM number arrived at with this formula must be factored by this percentage.

Next, you need to decide whether a vacuum secondary or a mechanical secondary carburetor will work best for you. As a rule of thumb, vacuum secondary carburetors work best on: Relatively heavy vehicles Street gearing Automatic transmission Engines built more for low-end torque Conversely, mechanical secondary carburetors seem to work best on: Relatively light vehicles Strip gearing (4.11 or numberically higher) Manual transmission Engines built more for top-end horsepower

The type of choke would be the next decision to face. Most of the Holley universal performance carburetors come equipped with either a manual or automatic electric choke. Manual chokes can be converted over to automatic electric choke operation with the proper Holley kit, and vice versa. Most automatic transmission kickdown linkage hookups will bolt directly to the carburetor throttle lever. Chrysler applications will require the purchase of bracket, P/N 20-7, if it's not already included with the carburetor. Those running the GM TH-700R4 automatic overdrive transmission will require the purchase of bracket, P/N 20-95, for this purpose.

Click on the links below for more Holley Carbs.

Remanufactured Performance Carburetors

New Street Avenger Carburetors Truck Avenger Carburetors

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