Backfiring through carb at low RPM

[70 RR]

I am having an issue that is driving me crazy. I recently installed a Modman intake dual quad setup to 542 stroker. I run an MSD distributor, 6AL, MSD wires, autolite 3934 plugs and to 1812 Eddy 800 cfm carbs. I posted a picture with my cam specs. I am running the heaviest advance springs with the blue bushing. Initial timing 22 and total is 35. I have tried running the carbs 1 to 1 and also progressive but having the same issue. Plugs are new and the wires are good (I know just because they are new doesn't mean they are good but what the hell).

If I accelerate (normal acceleration, not stabbing it) at about 2200 RPM in any gear I have a slight hesitation and my O2 meter spikes really lean(16-18). This lasts just long enough for the RPM to increase and then then back down to normal (12-13). During this time the car will hesitate and sometimes backfire through the carb. I have tried installing the largest fuel nozzle and swapping the blue metering rod springs from the orange ones from the factory. It seems to be worse with the blue springs so I changed them back, Edelbrock Tech support was the one that suggested the blue spring based on my cam specs. The car runs really well otherwise but I can't have it backfiring and stumbling around. Any ideas because I've hit a wall.....

 

[70 RR]

I changed from the heavy silver to blue advance springs and it seems to have solved my problem!

 

[coloradodave]

I am having an issue that is driving me crazy. I recently installed a Modman intake dual quad setup to 542 stroker. I run an MSD distributor, 6AL, MSD wires, autolite 3934 plugs and to 1812 Eddy 800 cfm carbs. I posted a picture with my cam specs. I am running the heaviest advance springs with the blue bushing. Initial timing 22 and total is 35.

FYI: The blue MSD bushing allows 21* of mechanical advance. So, if your initial is 22* you are actually running 43* total...

 

[70 RR]

You are right thanks. My initial timing is 17 degrees not 22 for a total of 38. That may be a bit high, I may change bushings to get it down to 35 or 36.