Picking the Right Carburetor

Picking the Right Carburetor

By Don Terrill (c) -

Comparing carburetors by their manufacturer's cfm ratings is the number one mistake racers make when picking a carburetor. In the old days it was easy - Holley was the only game in town. Today, with more competition has come more methods for rating carburetor air flow - It has become very hard to compare apples to apples.

I recommend that you don't even look at CFM numbers.

What needs to be decided and in what order:
  1. Air Flow Path Dimensions - Venturi and Throttle Plate diameters
  2. Type/Series - 4150, 4500 (Dominator), etc
  3. Manufacturer - Holley, Barry Grant, etc
  4. Linkage Style - Progressive, vacuum, 1:1, etc
  5. Booster Style - Down Leg, Annular Discharge, etc
Number one on that list is by far the most important decision you will make.

Questions that need to be answered:
  1. Engine Size - More cubic inches = more cfm (size) required.
  2. RPM - More rpm = more cfm (size) required.
  3. Application - Racing on limited tires and need to kill some lowend? Try a larger carburetor. Got'er hooked and need some more lowend? You got it, try a smaller carb.
Never, and I mean never: Loan or get rid of a good carburetor. They all have their own personality and some are just better than others.

Want to send off a nasty email about how wrong I am? Well, first read this and then write your own article.