Just got back from a car show in Plano Texas, "Cars and Coffee"  But the 68 making the drive home of 65 miles and my new headers were cooking the plug wires and the engine was missing out before we got home. The plug wire were extremely hot. 

Go under the headers.  Heat Rises!!!!  Use silicone plug wires.

Same here.  Went through 3 sets of wires already.  74 big block with headers.

In my case, because of the length of the wires; my problem is the boots.  I couldn't always route the best way or bend them enough so they don't touch the headers.

Here's what I'm doing next :
-get new set of boot protectors
-get the Summit Racing MOR-72550 wires (the price is right; I tried 125$ sets and burned them too).
-route the wires under the headers (the best I can) and use metal routing clips to help out; hold them in place.  Some of them are bolted with the head covers.  Some others are inside the spark plug hole; so it adds a later between the wire boot and the header.

And if it's still too hot; since my engine doesn't shine one bit and I don't display it; I'll wrap the headers.

Let us know what you do and how it works out.

Steph.

I use spark plug boots over the plug and wire leads, they are good to 1200 degrees and you can get them in colors, check out Summit, Jegs, or your auto parts store..Terry