Multiple positions for accelerator pump

[PaulC]

While dismembering my ADFA carb to refurbish,I noted that the accelerator pump lever had two positions it could be hinged to and were labeled 1and 2 with it being in the #2 position. Any idea why there are two? Maybe other models used the other location?

[davidbruce]

I believe you are correct. The different positions will alter when the pump shot starts and ends in relation to the butterfly's opening. It should be part of the specs just like jets,emulsion tubes etc. for a particular application but a quick search and I didn't see anyone who listed it in their specs.. That being said, that doesn't mean it is in the correct location. A PO could have put it back together incorrectly. Or it may function better in the other position due to the difference in modern fuels or engine mods. I suspect the difference would be subtle at best. Many Holley carbs use a plastic cam to activate the accelerator pump. Not only do they have multiple mounting holes but there are several different colors (profiles) for endless tuning options.

[manoa matt]

Keep it in the same position as removed.