my 340 duster is sick

One day I melted plug wires 5 & 7 on the headers. The car stated missing and the tach was bouncing all over the place. So I changed the two wires and this did not slove the problem. The car was hard to start and eventually wouldn't. So I pulled the plugs thinking they were fouled and replaced them. still no start, thinking no spark I changed the coil, still no start. So changed the coil wire and it started right up and ran ok for alittle while, then the tach problem came back. Still hard to start I checked the plugs again they were not fouled but smelled of gas. I tryed again to get her started and got a carb fart and white smoke out of the carb. Tryed some more and a very loud backfire occured. Got it running still the tach problem and missing. Not knowing whats going on she sat for awhile and when I tried again I got a repete of the carb fart. Is it electrical or carb relayted. Can anyone shed some light on what I need to do?  

Sounds electrical, you failed to mention if you had electronic ign. or points. If you have points I would check them to make sure they are gapped properly.
If you are running electronic ign. you will need to test the control box, or if you have a spare install it and see what happens.
The other possibility is a cracked cap.
Good luck
Doc  

Hey Doc thanks for getting back to me. One guy thought I had 5 & 7 out of sequence. I was 99.9% sure I didn't. So I switched them and would not start at all. Then I switched them back and got her started. Without a carb fart. She's still having the tach problem steady for alittle bit and then bouncing all over? I thought it was weird that after the 2 wires fried I had to replace coil wire. So being that the wires are missmacthed I'm going to replace them maybe the cap & rotor there a year or so old. I guess it could be cracked? I don't know how old the points are in the car so I got points allready but I don't know the gap? Would you? Some say a match book thickness. Anyway I hope i'ts that simple an  elec. glich in the system. I know these mopars can be touchy. thanks for all your info I know just enough to be dangerous. rick  

Its been 30 yrs since I gapped a set of point but 15 thousands would be safe. Be sure to put on some die electric greese on the rubbing block, or you will be regapping the points every two wks. for the rest of your life.
Doc.  

Cool doc. When you say rubbing block is that the dist. hex cam or the piece on the points?