View Full Version : Spark plug / rotor condition analysis

09-27-2009, 04:54 PM
Hey guys,

I'm looking for a second opinion on the state of my plugs and my rotor & distro contact posts.

These are pics of the plugs after a 2 hour highway run.

Also, is the wear on my rotor & contact posts normal? Should I replace them? The aren't that old; maybe 2-3k miles. ps, I have a pertronix system installed.

Sorry for the newbie question, and thanks in advance!

(can't find the pic i took of #1 btw)






09-27-2009, 06:35 PM
I'm new too, but will be interested in seeing the answer.

09-27-2009, 07:12 PM
I'd say from the location of the carbon on the rotor that your timing is too retarded, the rotor appears to have almost past the cap contacts before the spark occured.
As for the plugs, not bad, in my opinion, maybe 3 & 4 a little lean. Here's something you can use for comparison.

09-27-2009, 08:16 PM
I agree with PB. Put a light on it and move it ahead two degrees at a time. Or should I say "advance" it two degrees at a time until it is running better.

You can clean that right off with some steel wool.

09-27-2009, 10:22 PM
Richen up 3 & 4. You have insulator damage on plug 4.

09-28-2009, 08:43 AM
Thanks for the tips guys. PB- nice find on that spark plug chart. That one is much better than others I found online.

09-28-2009, 09:48 AM
I had the exact problem with my pertronix. I finally decided that the reluctor and pick up were slightly out of phase. It is non adjustable unlike the Crane.
They sent a replacement and the jury is still out, but it seems much better.

09-28-2009, 09:03 PM
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Richen up 3 &amp; 4. You have insulator damage on plug 4.[/QUOTE]

Agreed and I missed that damage on #4.

But check the timing first. If retarded, it can act too lean.