carburator poping

[pb24]

I just picked up a 68 charger that had been sitting for about a year, the previous owner thought the fuel pump went out and installed a electric one and never drove the car. I discovered that the accelerator pump wasn't working and rebuilt the carb. The car is running better but when I'm driving and put my foot to the floor I still get popping out of the carb and the car hesitates, I'm not sure if its a fuel issue or electrical, Also found out that the vacuum advance is working. What do you think could be wrong

[Chryco Psycho]

generally it is a sign that the carb is going lean so it either needs more squirt , higher float level , bigger jetting or there is a bockage in the jet circuit 

[myk]

Could there be any ignition problems here also?

[HS-68charger]

On my 68, I had been fighting this problem as well except it also happened alot from a dead stop (I have a 4sp).  I bumped my timing to 20 degrees initial (I have an FBO curved dist) which helped alot, but I still was getting that damn backfire through the carb!

I even threw on a freshly rebuilt 750 dp to replace my old 750 vac. sec since the old Holley had been sitting on a shelf for over two years!  It still did the same thing with the dp.  I finally took the advice of some people and put a bigger squirter in the 750 vac sec.  I went from .31 to .35.  That finally did it! No hesitation and no more backfire.

As already recommended, try bumping the size of your squirter by 4 sizes.  I believe I read that you should increase the size by 4 somewhere in a Holley tuning book or maybe from Holley themselves.  Anyway, it worked for me.

Good Luck!