Slight popping out of carb

[ALS71GS]

  Hello q-jet enthusiast's! I have not posted on this sight much but have learned much from this sight as well as Cliff's book.
The carb I just rebuilt with a h.p. kit from Cliff is #17056540. After tuning and getting idle right,a couple of times under hard acceleration on the primaries engine has popped through  the carb. Could this from to strong of spring on acc. pump?

 Engine is a 462 Buick ,Ported iron heads, 9 to 1 comp.,performer intake,228/236 cam.
 
  Thanks in advance for any ideas

[Cliff Ruggles]

A strong pump spring on the pump improves fuel delivery.  Popping up thru the carb is most often a lean condition, or ignition problem.....Cliff

[ALS71GS]

Hi Cliff,so if this popping might be a lean condition,should i try different metering rods? Or is there another solution? Jets are 73 with rods from your shop.
Accelerator pump holes are at .031.Also engine is operating on manifold vac. advance.
Thanks Al.

[429bbf]

how did it run before you overhauled the carb?did you just build the engine?look for a vacuum leak of some sort . kind of the same symptoms i had today except all three of my caps were leaking they had split open. fwiw

[ALS71GS]

429...This carb. is new to engine. Last carb. had no provision for electric choke and some other issues but otherwise ran pretty well.However driving the car today I could not repeat the popping condition but still has slight hesitation on very slight throttle opening.I think I will try raising APT setting.

[77cruiser]

What's your timing like?

[ALS71GS]

Timing is 32 total mechanical,10 on vacuum can, on manifold source.

[Cliff Ruggles]

The vacuum advance isn't a player at heavy/full throttle so where you hook it up at doesn't matter.  Same with the APT, it doesn't adjust fuel delivery other than very light throttle/light load.....Cliff

[ALS71GS]

  Cliff, I do have a very slight stumble/hesitation just off idle,under very light throttle,more noticeable bef cure this?ore fully warmed up.Will a higher apt setting cure this?

[77cruiser]

What's your initial timing? Maybe try about 4 more degrees. Adjusting  the APT up might help too.

[ALS71GS]

Thanks for the reply cruiser...my last post was a jumbled mess (computer has a mind of its own) .Should of read, Cliff I do have a very slight stumble / hesitation just off idle under very light throttle, more noticeable before car is fully warmed up,will a higher apt setting cure this?
  I think initial timing is 14 btdc with 10 from vacuum can (manifold source )
 Thanks Al

[blazer74]

Raising the apt can help.

Pump shot, are you on the outer hole.

At one time  I inadvertantly put the lever on the inner hole and had similar symptoms.

[Frank400]

Pump shot, are you on the outer hole.

At one time  I inadvertantly put the lever on the inner hole and had similar symptoms.

    you definitely WANT to  be on the INNER hole.  Inner hole will give more fuel per pump stroke.

[dlong70elcamino]

I had this problem with my Q JET on my built 350 Chevy. More timing and set the secondary air door spring 1/4 turn tighter and it fixed it. Its launching at the drag strip no backfire no hesitation at all. Hope it helps .....Dan

[blazer74]

    you definitely WANT to  be on the INNER hole.  Inner hole will give more fuel per pump stroke.

YES, the inner hole. I had a moment, my apologies.