So I'm driving a 1969 4 door Impala. I put headers on it a few days ago, and the #6 plug is touching the header. The first wire got melted thru (causing it to misfire and run on 7 cylinders), so we put on an excel header plug, so it would have more clearence. But even with the clearance, it still stutters a bit while driving, making it seem like it's still running off 7 cylinders. All the plug wires are fine, but it's still running weird.

Could it be the points and condensor? Or something else?

 

The Spark Plug should not be touching the header.... Headers rarely fit perfect from the factory... Usually you will have to clearence them some.... I have found the best way to do this is to mark the header where it needs to be clearenced. Then remove the headers. take a Old Deep wall Socket (I use a 5/8 spark plug socket) that you do mind hitting with a hammer and place on the surface on the header about the same angle of the plug (So you clearence where the wire will be) the get a buddy to hit it with a hammer while you are holding it in place. On the number 6 you will probably have to clearence the area of the header that is almost running parallel with the head. This will also make it easier to change the plugs later. the Number 6 is probably the worse one so any clearence you have will help... Also look into excel Armor Plug wires they have a tougher material that is supposed to help with this same problem.

Now for the problem with a good wire but still running on 7 cylinders.... when the spark was jumping straight to the header and not going to the plug it probably caused the spark plug to foul. I would check/change all the plugs to see if that fixes your problem.

 

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Good Luck