Backfire under load

[jkaiser51]

I am currently trying to figure out a popping noise when bringing rpms higher in park. I own a 71 Charger with a 440 in it. It starts up like a champ but when bringing up rpm it pops out of exhaust. Also when put into drive and giving gas it falls on its face and kills itself. Any help would be appreciated. Have a video of popping but don’t know how to post in thread.

 

[70chall440]

1. check for vacuum leaks: use some carb cleaner and spray around the base and any/all ports, if the engine RPM raises you have a leak.

2. check the timing: make sure this is both set correctly and responds steadily. If the distributor is worn it can through off the timing and cause issues.

 

[WileE]

What are your vacuum readings ? At idle, and through the RPM range. What is your timing set at ? At idle, and through full advance to what RPM ?

 

[chescharger]

Are the plug wires correct ?

 

[turbine68rt]

Can you give a little more info such as what carb and ignition type you're using?