Virtually all aftermarket carburetors come in the "one size fits none" category out of the box. They must be tuned for a specific engine displacement, intake manifold, camshaft, cylinder head, and exhaust configuration. That includes Holley, Edelbrock, Weber, and a bunch of others. (Yes, even Carter!) Some purchasers are willing to accept half-donkey performance, as long as the engine starts, idles, and more or less runs at midrange and full throttle, so it's "good" in their opinion. Since they don't have the knowledge, skill, or test facilities to evaluate whether or not they're getting the best fuel mixture for a variety of operating ranges, they're satisfied with whatever the carb manufacturer chooses to give them. One point of reference- - - -in racing applications, Holleys are easier and less expensive to tweak for better performance than Edelbrocks. Holley main jets and power valves are plentiful and less expensive than Edelbrock metering rods and springs. They also have different volume accelerator pumps and pump operating cams to adjust the pump shot. If the carburetor the engine manufacturer spent millions of dollars of R&D money on isn't sufficient for some reason, the hotrodder with a box of wrenches and screwdrivers and an "I'm smarter than all the engineers" attitude probably deserves what he gets. That's particularly true if he has a computer and he can Google up a few dozen articles written by some unknown "expert" to support his delusions of intelligence.
Jerry
