Carb accelerator pump question ?

[pearljam724]

On a 4 barrel Edlebrock Thunder Series carb what is the purpose of the 3 accelerator pump adjustment holes ? I realize it makes the accelerator pump plung further or not as far when moving it from one hole to the next.
But, why would anyone want to adjust it ?

 

[HEMI-ITIS]

To adjust the timing of the pump shot.

 

[pearljam724]

To adjust the timing of the pump shot.

Thank you. But, what does that accomplish ? Makes the car more or less responsive once you hit the pedal ?
Originally, it was in middle hole, if I try moving it to either of the other 2. The pump doesn’t want to retract smoothly or I can’t start the car if it’s in the top or bottom hole ?

 

[beanhead]

Some cars need the shot to hit later, or sooner, to give the right amount of fuel at just the right time to avoid a bog or stumble.

 

[Bee1971]

https://edelbrock-instructions-v1.s3.amazonaws.com/edelbrock/carb-tuning-guide.pdf
CALIBRATING THE PUMP
If you encounter any hesitations or stumbles that do not seem to be related to the basic metering or have not responded to changes in the basic metering, move the pump drive link to one of the holes closer to the carburetor body. This will increase the stroke length of the plunger and result in more pump delivery.

 

[BSB67]

It's not when. Its duration/total delivery.

More shot than needed will hurt performance, but likely unnoticeable for the average street guy. Too little and could get lean hesitation. Honestly, all the AFB, AVS, Eddy/Carter like carbs I've messed with, I could not feel any difference on the street.

If you were track tuning, you might see it in the 60 ft time. On your AF meter you might see it too.

 

[HEMI-ITIS]

On a 4 barrel Edlebrock Thunder Series carb what is the purpose of the 3 accelerator pump adjustment holes ? I realize it makes the accelerator pump plung further or not as far when moving it from one hole to the next.
But, why would anyone want to adjust it ?

View attachment 856701

Are you having an issue that would make you ask? I was always a Holley guy

 

[pearljam724]

Thank you, to all. No problems. I thought what you guys confirmed. I wanted to play around at each adjustment to see if I noticed better or worst throttle response. But, for a while there I couldn’t get it to start because I think I flooded it playing around with it. Would the setting you choose effect fuel mileage one way or the other ?

 

[HEMI-ITIS]

Depends how often the pedal hits the floor