Backfire through carb

[j_oetjens]

Any suggestions would be appreciated

I have a 1980 el camino I'm getting back fire through primaries when I floor it while parked in driveway and also when I drive and floor it. No backfire if I slowly accelerate in park or driving. When parked secondaries barely open at WOT. it has a rebuilt gm goodwrench performance 350. These are most of the specs:

Carburetor from 1975 Oldsmobile Cutlass 455
M4MC Rochester Quadrajet 7045183

Following cliffs book here are carb adjustments

Idle tubes 1.0mm / 0.0394
Idle down channel 1.5mm / 0.0591
Main air bleed main body 1.8mm / 0.071
Main air bleed air horn 1.8mm / 0.071
Lower idle air bleed main body 1.8mm / 0.071
No idle air bypass
Air horn milled
No choke
Primary 75 jets 45b rods
Hanger F 0.540
Secondary rods CV 0.0527
Secondary flaps tension spring set at 1/4 turn.
Idle mixture screws 3 turns out set at highest vacuum and highest rpm.
Base timing 18

[Cliff Ruggles]

"B" series primary rods are incorrect for that unit.  I would get our 44 primary rods instead.

Team that up with the good accl pump from our SR kit, new secondary cam/spring and timed choke pull-off and I'll bet all those lean backfire issues disappear......Cliff

[j_oetjens]

Thank you for the quick response Just to check the SR kit comes with accl pump and new cam/spring for secondary. I have 41j rods but got a lot of gas smell from exhaust. So I will get 44 rods. My choke pull off holds vacuum but vacuum from engine doesn't keep it fully pulled. Will the new choke pull  off be able to hold better 

[Cliff Ruggles]

Yes the new pull-off will hold fine.  75 jets are huge in one of those units so not surprised it was stinky with 41 rods in it.....

[j_oetjens]

Thank you will be ordering parts