IMHO, there is nothing wrong with Edelbrock (aka Carter/Weber) carbs. They perform fine, they do the job just as well as any carb does. They tune differently than Hollies and this is where the bad press comes from. Holley uses a power valve for fuel enrichment under load, Edelbrock uses meter rods. Both methods serve their purpose and provide fuel enrichment under load conditions. However they tune differently, and this is where the confusion and trouble comes from.
Most of us do not take the time to fully understand the functions and operations of a carb, let alone two different designs. Hollies are more forgiving in some areas, while Edelbrock are in other areas (function & tuning). I've used both designs on numerous vehicles and like them both. The caveat with either design is tuning. A carb is a mechanical device the meters fuel into the engine via linkages and vacuum (manifold and venturi), for it to function and give the best performance it must be tuned to operate within its perimeter to the engine it is installed on. Remember the guy you went to school with that always had the faster car? Even when someone else had the same make and model his was faster. SECRET, he knew how to tune.
"Stovens" back to your question about accelerator pump fitting.
Edelbrock uses two different pumps, the only difference is the spring, a weaker spring is used on the smaller carbs, a stonger spring on the larger carbs. Length and diameter are the same, adjustments are made to the linkage arm to tune the pumps operation (three holes), but also the linkage rod can be bent at the knee to further adjust the pumps action. And, keep in mind the two spring tensions can be used to aid in tune as well. The weaker spring will produce a lazier but longer duration of fuel (slower/longer squirt), the stronger spring will be quicker with less duration (sooner/shorter squirt).
BUT, before we get into pump tuning, let's make sure there isn't another tuning issue first. Believe it or not, a lot of carb issue are caused by the ignition. Low initial timing can cause the carb's throttle stop to be adjusted too high (idle speed adjustment) to raise idle RPM, when this happens the carb is operating partially through the transition circuit and when you accelerate there is insufficient fuel enrichment to prevent a lean stumble. The solution is to raise initial timing and lower the throttle stop adjustment. More initial time will raise the idle speed allowing the carb’s throttle stop to be lowered and operate on the idle circuit (mixture screws), then as the throttle picks up the transition circuit adds fuel along with the accelerator pump, enriching the fuel mixture and preventing a lean stumble.
The caveat with ignition timing is, when you adjust initial timing (up or down) TOTAL timing must be checked and adjusted if needed.
Sorry for the book……….