destroyed ignition rotor, Bosch Spider

["Dean W. Cains" <dwc@xxxxxx>]

Hi Group:

Last night I removed the distributor cap from my '87 Spider, to allow 
easier access to the coolant bypass hose, which I was replacing.  I was 
amazed to see that the ignition rotor, actually the end of the rotor that 
the spark jumps from, was burned down to barely a nub.  There is perhaps 
3/8" of the tip that's just gone.  Here's the background info:

Last December, shortly after I bought the car, I replaced all the ignition 
tune-up parts.  The cap and rotor are the ITAB brand, from Centerline.  The 
plugs are Bosch Platinum WR7DP (the single-electrode type), and the coil is 
original to the car.  The wires are made by Aurora, and are Magnecore 
clones, which is to say that they don't have the metal-shielded resistor 
spark plug connectors that the OEM wires have.

http://www.auroraignitionwires.com/auroraignitionwires.htm

Without making any assumptions yet, obviously the only difference from OEM 
configuration is the different plug wires.  When I removed the old parts, 
before replacing them with the new stuff listed above, they were well-worn, 
but certainly had some use left, and nothing extreme jumped out at me.

As for the new parts, after I saw the state of the rotor, I thought perhaps 
the tip had contacted the inside of the cap, and broken right after I 
installed it.  But, I can't see any damage inside the cap that would be 
evidence of that.  The brass contacts look untouched, but the inside of the 
cap looks slightly burnt, presumably from all those extra-large sparks 
jumping from the abbreviated rotor tip.  The rotor tip looks like it's been 
hit with an acetylene torch.  There is an almost imperceptible amount of 
lateral play that I can feel in the distributor shaft, but it can't be more 
than a few thousandths of an inch.

Any educated guesses as to what happened here?  The new parts have less 
than 1,500 miles of use.  Is it the different wires?  Actually, before I 
purchased the wires, I asked the Digest if anyone had experienced problems 
with non-OEM wires, and several guys said it was OK to use any good-quality 
wires.  The strange thing is that the engine still starts instantly, and it 
idles and runs just as well as ever, although I'm not driving it again 
until the problem is solved.

Regards,

Dean
Lutz, FL
'74 & '87 Spider Veloce's
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