Stuble and pop when hot off the line

[Barry_Calgary]

Hi All,
My 73 RR with a 440 runs awesome most of the time but strangely when you sit at the lights for a minute or two then put your foot down it pops and hesitates before it takes off.
It definitely seems that it is an accelerator circuit issue but it doesn't do it any other time other than when it idles or if you are cruising for a minute or two then put your foot down.
It has a Holley 750 with a 1" spacer. From what I have read online changing the carb spacer for 1/2" spacer may help. Could it be something to do with the accelerator pump? but why only after sitting for a while in gear? Could the fuel burn off in the accelerator circuit when idling?
Thanks
Barry

 

[Ernie ingling]

Could be a little lean?

 

[Scott Engelhardt]

Is that a Holley Avenger carb? If so what color is you accelerator pump cam. How hard are you stepping on the gas? My Avenger carb had a tip in stumble I could not tune out. I did learn to live with it because it works so good every where else.
There is a larger CC pump you can try. Have you checked your power valve? There is a good guide online on what valve to use for the vacuum you have at idle.

 

[TN Mopar]

I agree it sounds lean to me
I wouldn't change the spacer until I tuned the carb
Accelerator Pump cam and possibly larger squirter nozzles
I had to do this to my avenger
also possible is the 50cc pump but it is most likely the cam and squirters will fix your problem
Also you may need fatter front jets

 

[Don Frelier]

You don't have iron manifolds with a stuck heat riser valve?

 

[69L48Z27]

Man I hope the OP wasn’t waiting from 2015 for help.

Barry hasn’t been seen in 3 years.

 

[TN Mopar]

Man I hope the OP wasn’t waiting from 2015 for help.

Barry hasn’t been seen in 3 years.

LOL I didn't even notice that

 

[Don Frelier]

Ok I'm changing my answer to old gas.