Plug Wires touching
 

My car started running really rough and the guy at the shop i brought it to said it was because it was miss firing. He also said it was because some of the wires could have been touching eachother. But when i went to seperate them i found the #3 plug wire was burnt from my header. Does it really matter if the wires touch one another?

YES!!!

That is one of Fords biggest mistakes. The firing orders available for their V8 engines both have sequentially fired cylinders that are next to each other on the same bank, which means they are more likely to have a misfire if the wires are touching. Specifically, wires #5 & #6 on the HO engines and the 351's, and wires #7 & #8 on the non-HO engines.

:)

Take care,
-Chris

What about the 9mm wires? I've heard that they have a little more protection around them so its not as big of a deal if they are touching.

How hard is it to install a $3 set of separators?

I don't care if they are 20mm wires. Separate them. Besides, it looks SO MUCH BETTER anyway.

But hey, it's your engine.

:)

Take care,
-Chris

#3 is the most typical to burn, especially with MAC equals. If it burnt once, it will probably burn again. I suggest you get yourself some spark plug boot protectors. These should protect them from burning again.

I have seperators and 9mm wires but there are still places where two wires can come in contact. Thanks for everyones help.

Its not so much that they touch, its when they run parallel with each other for a long distance .... when they do, high voltage flowing through one can induce current flow in the one running along side it, if theyare close enough together for a long enough distance ... like pkrwud says if that occurs with two cylinders that fire close together you can have problems. Put a seperator on them and keep them apart. I put the # 7 wire on one side of the seperator and the # 8 on the opposite side to keep them as far apart as i can.
Some basic electronics in a nutshell ... if you run wires, especially high voltage wires side by side, close together for a long distance, current flow in one will cause current flow in the other, insulated or not.

I had trouble separating mine at first too. But then I just took them all off and installed them one at a time, planning where my separator was going to be most effective and how I could run each wire so it didn't touch. Now it looks good and I don't have to worry about it as a source of detonation and they look better!