What is the best way to determine if your plugs wires need to be replaced?? I have a set of Jacobs on my SB409 that are two seasons old but have only seen about 2500 miles of run time. I have concerns that the wire on #6 may be bad as that plug seems to be a bit darker than the rest and the pass side exhaust sounds to be off or missing slightly. If I need to replace my current wires What wires do you guys like say in the $50-90 range. Has anyone done the under the header routing of plug wires, any suggestions on what has worked for you??

BTW I am running a GM HEI with a Pertronix module and MSD in cap coil and AC/Delco Rapidfire 7 plugs.

I like to look at them with the car running in the dark to check for leakage, which is quite colorful when present. If I suspect a dead cylinder, I'll measure the resistance in the wire, looking for a very high reading as compared to the others.

Move that wire to a different cylinder and see if a fresh plug gets all dirty. If it follows the wire, you need wires graemlins/thumbsup.gif

-Mark.

Thx Mark, that makes good sense. I will try it in the next day or two and see what happens! Tom

bowtie,
Look in a service manual(usualy under the tune up section) it will tell you about how many ohms of resistance a wire should have(you'll need an ohm meter). The length of the wire will be a factor on how much resistance that wire is allowed. I cant remember off the top of my head or I'd just tell you and I'm at work so I cant look it up for you. Hope this helps, Nick

If you need wires i would suggest the MSD 8.5 super conducters. They are a darn fine wire and that is what I run.

bowtie,
Here's whats in my sevice manual for HEI ignition
00-15 inches Min is 3000 ohms Max is 10,000 ohms
15-25 inches Min is 4000 ohms Max is 15,000 ohms
25-35 inches Min is 6000 omhs Max is 20,000 ohms
over 35 it list no Min but Max is 25,00 ohms