Popping, backfiring through carb and exhaust.

[mamatried01]

Have had this problem for awhile. 1968 383, 2 barrel

I changed to the Pertronix ignition,  new Distributer with new Vac Adv. Carb rebuilt. Problem persists.
It seems to do it no matter where the timing is set.

[tecmopar]

If it does this at idle, unplug the plug wires, try going one by one and see if you can isolate which cylinder it is. Sounds like you may have a couple of bad valves. sometimes a bad distributor cap will cause this but you said you changed that, good luck.

[whitehatspecial]

I had a similar problem and it was one of the "champion" plug's porcelin insulator that came loose.

[74340charger]

I had that problem everytime I changed my engine last year, it was 180 out, so a very simple fix. I hope that is all it is for you.

[tecmopar]

I may have misunderstood because you said you have had this problem for a while---does the motor run or are you trying to get it running.

[mamatried01]

I may have misunderstood because you said you have had this problem for a while---does the motor run or are you trying to get it running.

It is currently running. Seems to idle ok. Under load it does this.
Got a few things to try now. Thanks.
I'll try to look at it this weekend.

[resq302]

Our el camino did the same problem.  Turns out it was a bad rebuild on the carb and was leaking gas internally into the engine at idle and would have the same effect like you are.

[firefighter3931]

It sounds like the engine is going lean. Check the float levels to make sure it's not running out of fuel. You might have to adjust jetting if the problem persists. Pull a few plugs to see what kind of color you have on them. Light grey/white means the jetting is lean. Light brown/tan is good. Dark brown/black means your too rich.

The base timing at idle should be at least 10* if not more. 5* isn't enough.



Ron

[mamatried01]

It sounds like the engine is going lean. Check the float levels to make sure it's not running out of fuel. You might have to adjust jetting if the problem persists. Pull a few plugs to see what kind of color you have on them. Light grey/white means the jetting is lean. Light brown/tan is good. Dark brown/black means your too rich.

The base timing at idle should be at least 10* if not more. 5* isn't enough.



Ron

Thanks Ron, I'll look into that.

[68chrgrwife]

we had the same problem with the challenger..we opened the vac advance all the way and it stopped, but it isn't a complete fix.

[RogerDodger]

I had one that backfired while running. It turned out to be the timing chain had jumped.

[GreenMachine]

I don't know how the Pertronix is wired, but on an electronic dist., if the 2 wires are reversed it will do something like that.