Stalls while driving and pops and backfires then starts and runs fine again

[motoreese]

I have a '78 440 I build 40 over with proform 750 double pumper. The car runs fantastic at least it did...
One day I'm driving and stop at red light and she dies out of the blue. I try to start her and she was unusually difficult to start but she finally did and I drove normal and everything was fine. Weird!?!

So I'm coming down the high way yesterday and all of a sudden she back fires out the exhaust like a shot gun blast, I look down and tach is at 0 then goes to 3k then back to 0 and she backfires again, then tach goes to 3 again, this happens 4 or 5 times as I pull on to the shoulder she starts up again tach at 2500 (I was slowing down) and she drove smooth as anything again all the way home.
Now I've noticed that periodically I will try to start her with normal one pump of gas and won't start. I crack once or twice more she back fires out the exhaust like a gun shot and starts idles fine sounds wonderful!
Any help anyone?
Ideas??
Thank you so much gentlemen!

[1974dodgecharger]

Sounds rich and or ignition is bad.

[motoreese]

The carburator is brand new and has been running for only a few months and it just started, all ignition components distributor, cap, plugs, wires, ignition module, all only have 1000 miles on them. This is why I'm stumped, it's all new stuff and has been running fine up till about a month or so ago?

[BLK 68 R/T]

What ignition are you running? Also, have you pulled a plug out and cranked it over to see what the spark looks like? If you are running the mopar orange ignition box replace it with a chrome one to start with. If that does nothing I would try a new coil.

[motoreese]

Yes it's the orange ignition module. No I haven't checked spark plug yet and coil is autozone special lol
First thing I thought was possibly the coil as I went through 2 different ones from autozone till I got one that worked!
Guess a new coil might be first thing! Accel a decent brand?

[BLK 68 R/T]

Far as I know Accel is a descent brand. I thought of something else you might look at before you buy anything. Check to make sure you have a good ground on the ignition box. The orange boxes are know to have issues so that is why I suggested you start with that before the coil after you make sure the ground is good.

[motoreese]

http://m.summitracing.com/parts/dcc-4120534

[TexasStroker]

Power valve is probably shot and every time I've seen this in my own car and friends it has been the distributor cap or coil.  I've always had it be the cap, even thought it looks fantastic and has good contacts...other rides I've fixed usually have a crappy coil and/or bad ignition box.

[c00nhunterjoe]

If the tach drops to 0, i would be looking at a lost connection. Even if it stalls, the engine should keep spinning while its in gear. Unless it is a super loose converter, but doesnt sound like it in this case. Think about the physics, if the tach drops to 0 and you dont hit the key, how did it restart itself and go back to 3000 rpm? Sounds like you are losing power or ground intermittently.

[firefighter3931]

  with Joe....sounds like an electrical connector/ground is loose somewhere.   



Ron