discharge nozzles

[knudsonm]

Here is the problem I\'m having with my new carb. I have a Holley 3310 - 750 vac sec/mech choke. I have a stumble/intake backfire just off idle and I talked to Holley about it and they told me to change the discharge nozzle from a 31 to a 37. So I changed it and it still has the stumble/intake backfire. What else could I try beside an even bigger discharge nozzle? Could it be timing? I have it set at 16 degrees initial and 36 total mechanical. I get about 45-50 with the vacuum advance. Could it be the pump cam? I\'m using the one the carb came with stock.

[basementdweller]

45 - 50 is WAAAAAAAAAAAAAAAAYYYYYYYYYY TO MUCH TIMING!!!!!!!!!!! Try playing with the accelerator pump lever see how much play is on it. If you can wiggle the lever back and forth (NOT UP AND DOWN) its too loose, hard to describe in words but open the throttle VERY SLOWLY and see if the accelerator pump lever is moving when you begin to move the throttle, if not.. losen that bolt (that should tighten it up). That can be a major cause of backfire or sputtering right off idle.If you need further help, email me and if need be i will try to snap pics and point out what im talking about, or i can possibly make an MPeG and ill show you with another carb.