Charger backfiring intermittently

[timinator]

My 68 Charger is giving me problems. It's a fresh rebuilt 440 with about 2000 miles. It has the mopar electronic ignition and a new Edlebrock 750 carb. It usually runs great but several times over the past few years it sputters, backfires and quits running. It did this again last fall and luckily I was able to coast home and park it. I just fired it up again and it's still doing it. I've checked all the electrical connections and they look good. I swapped out the plug wires and coil  from my other Charger which didn't help. The gas is fresh. Where do I start looking?

[1BAD68]

two things that may not pertain to you but you should check anyway.
Make sure the distributor is grounded good, this left me stranded last summer.
Also double check your distributor cap or just replace it, it can cause intermittant firing and backfiring and all kinds of weird things, see video....
http://www.youtube.com/watch?v=Jf3rmPwABR8

[Steve P.]

Does this happen at any temperatures? Cold start up right through to warmed up? Or is it after it is warmed up?

A poorly grounded distributor can definitely do this. Also a non-vented cap can do this when you have allot of resistance in your tune-up. (Bad wires, coil, plugs not gaped right, even loose plugs).

Poor fuel volume. (Lean out). Starving the cylinders..

Improper ground to the ignition box.

Sticking valves.

Many thing can cause this problem..  I would start with making sure everything is grounded well. Many people don't bother with a ground strap from the motor to the firewall. This is a HUGE mistake. Make sure you have excellent grounds from the battery to the motor. Motor to the firewall.

Make sure you are getting a good ground AT the distributor. Some use a flat washer or NO washer on the dizzy bolt. I like to use a spider washer. They have teeth and bite in like a shark. Also make sure the Dizzy bolt is tight.

How good is your fuel system? Tank, lines, filters and pump are all things that need to work well. You could starve the carb for fuel and end up with this exact condition.  Carb itself could be the culprit. Any gum or varnish that has formed can do this.

Start with the simple things. many times it is something simple that broke or just got overlooked.

Let us know..

[Tilar]

Is it backfiring through the exhaust or the intake? Does it do it when you are putting it under power or does it do it at a steady cruising speed?

[timinator]

It seems to do it both cold and warm. I've only noticed it under part throttle conditions though. It backfires thru the exhaust. I'm thinking electrical so I'll check the grounds first. It's not the cap or plugs since I swapped them out with my other Charger that runs fine. I need to fix it before I wreck the thing. I was going around a corner last week when it cut out and stalled. I lost my power steering and brakes and almost hit a parked car!

[Steve P.]

The car cutting out going around a corner makes it sound more like a low fuel problem. Definitely check everything. If you find something wrong fix it, but don't stop there. Normally a LEAN running motor will back fire through the carb., but the fact the it died turning a corner makes me thing not enough fuel. Also the part throttle.

Let us know how you do...

[Tilar]

It almost sounds like a broken valve spring but that would tend to make a clattering noise at higher than idle speeds, but I wouldnt think it would make the engine die.

Another thing would be like Steve P. mentioned. You might check your fuel pressure and volume.