NEED OPINIONS

[kathyscuda]

this is a first.i can usually figure any problem out.
70 cuda..fresh 340.. 4 speed..orig rebuilt carter afb. ..petronix ignition..
starts fine,,idles fine.. drives fine,, ..

in 2nd or 3rd gear cruising along I decide to put it to the test and it feels like half the plug wires were pulled off.
so I let off and its fine .
I tried. different plugs,different wires,different distr.put a points distr back in,  then I thought broken valve spring. nope. compression test all ok .
all the plugs have a nice shade o grey .
its kinda like the secondarys are butterflying if that makes sense.{ vacuum secondary's }
I DONT FUNNING KNOW ??

[RUNCHARGER]

Adjust the air door on your AVS carb. It's opening too fast causing a stumble most likely.

[70 Challenger Lover]

So when you say it feels like half the plug wires were pulled off, does that mean there is misfiring in the ignition system or is it that it simply lacks power as though the throttle wasn't opening all the way?

[Cuda Cody]

Might be leaning out under load?  Is this a new carburetor?

[kathyscuda]

its the orig carter, ## ????
it feels like a misfire. but everything electric was double checked or replaced to test. coil etc.
im also thinking secondary door not adjusted properly. I did read up on adjudting it. bending the rod a little .

[kathyscuda]

runc , I will mess with the air door.
I set it to the book. I think it was around 1.5 turns and lock the screw. ?? I may have to go a little more .. put more pressure on it ..

[Spikedog08]

Sounds like a lack of gas . . Carb needs dialed in?   

[bennydodge]

Maybe the fuel filter as well. I've had better luck with the reproduction metal ones. Also, make sure the float drop is right. If the floats don't drop far enough, the fuel fill into the carb will be slower and cause some of the problems you described.

[jimynick]

Don't discount the ignition as the cause yet. I had a 340 that began to misfire and it was because the ignition wasn't receiving enough voltage. It began when I got on it, as that challenges the ignition beyond what it took to just run along. May not be the cause, but checking couldn't hurt, could it? Good luck! 

[70 Challenger Lover]

Or the advance in the distributor is stuck.

[Chryco Psycho]

What changed ? Was it running well & you or it changed ?
Flaot level is the first thing that comes to mind it should be 7/32 I usually set it at 3/16

[kathyscuda]

float height is correct . took carb apart twice. .i will try a new fuel filter. it is metal and not that old. I even put some race gas in  it.
keep picking at it

[Rich G.]

Do you have a spare coil to try it even a single point distributor to try. My guess would be ignition breaking down under a load. The only 2 pertronix I've used broke down.

[Chryco Psycho]

I have had pertronics fail also but you have to connect the power to 13v not to the positive coil feed as it is only 7v which will cause the unit to fail