I just started getting my car ready for the summer and took it for a drive. When I start the car up sometimes it backfires out of the carb. Also if its starting to stall on me as I warm it up Ill give it some gas and it will backfire out of the carb and stall. I stomped it while driving and it just lagged and almost stalled and then I got the pick up. I am assuming that I am running rich. The fuel pressure is at about 5.5LBS. All specs in sig. Also, where should I start when adjusting the carb A/F. Do I need to shut the secondaries first... begin with primaries? It's a Holley 750 DP. Thanks.

 

Check your ignition timing
If its 2 advanced youll get detonation will the intake valves are still open.
Now one thing to rember is your ignition will automatically advance a few degrees at part throttle and even more at around 2000 RPM to its max of up to around 30 degrees.
Get out a timing light and set your ignition to around 8-10 advanced at idle.

If you want to do the math and get real in2 it, it takes 0.003 seconds for combustion to occure and your cam will turn 18degries at 1000rpm in 0.003s.
(your distributor shaft is driven off the cam witch turns 1/2 the speed of the crank)

 

Backfireing through the carb when you stab the gas means its lean. Increase the accelerator pump shooter size.
More initial timing will help too.