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John S
08-24-2008, 09:16 AM
I'm working on a timing issue and when I popped off the cap I found this. Before I put it all back together I was hoping to identify the cause of the problem.
I did find one wire that was burnt pretty good, is it possible for one wire to arc through another and back into the cap/rotor?

I'm running a MSD 6, blaster coil and FAST dual sync distributor with MSD 8.5 wires.
Ok, I'm working on a timing issue and found this when I popped the cap off.
I'm open to opinions what might cause this :stupid2:
https://static1.pt-content.com/images/pt/2008/08/DSCN0160-1.jpg

mpozzi
08-24-2008, 09:42 AM
Too much air gap somewhere, or way too much resistance. Make sure all of the primary and secondary ignition circuit connections are sound.

You mention a burnt wire. Plug wire, by chance? Check the rotor terminal and if it's firing in the center. If it's off to one side, there may be a polarity and/or phasing issue. With the MSD, that's a hella arc ... surprised the engine ran.

Good luck,
Mary Pozzi

David Pozzi
08-24-2008, 10:20 AM
Install the distributor, set timing, stop engine and bump it around to where the marks on damper and timing cover show the same as the timing at idle. Remove the cap and mark the outside of the distributor body to show where the rotor tip is pointing. Replace the cap and observe where the rotor is in relation to the plug wire contact. You probably have a rotor phasing issue or the timing was WAY off. A clear type plastic cap or cut away stock cap can be used to help observe rotor to terminal phasing.

Rotor phasing can be caused by reversing the two wires from the pickup coil in the distributor. It will cause the ignition to fire when the rotor is half way between the plug terminals. It also causes overheating of the ignition amplifier and can shut down the ignition until it cools. It happened to me.
David

John S
08-24-2008, 05:11 PM
MAry/David;
thanks for the replies, here is a bit more information.
This setup has been running in the car for the past year, the only change is removing and re-installing the distributor after a cam swap a couple of months ago.
Primary and secondary is sound and intact.
The burnt wire was the #6 plug wire from contacting the header. thats been resolved by rerouting the new wire and installing wire covers.
The car started running a bit rough on the way back from a cruise. I was checking the timing and noticed that the timing light was firing erraticaly and I could not tell where the timeing actually was.
I Found the burnt wire and decided to replace them all along with the cap and rotor. Thats when i discovered the damaged rotor.
David, can you explain a bit more about phasing the rotor? I can cut the top out of the old cap to check it.
Once timing is set @ 28* are you saying that the rotor should be centered on the terminal for the #1 cylinder? Would the fact that the XFI controls the spark have any bearing on this?
Thanks for the help,
John