OK I've been having some problems lately so I pulled my plugs. They all looked the same. The rim around the plug had black carbon on it. The side electrode (the one that comes off the rim and goes over the center) had grey deposits in various shades. The center electrode also had grey deposits, and one side of it (and the same side of the tip of the side electrode) had shiny grey/black deposits almost like I'd shot it with spray paint or something.

Also they are Bosch Platinum's, they were almost 1/8 inch shorter than the Delco ordinary ones (the ones the dealer recommended) I replaced them with. Someone told me platinum ones burn a little differently but THAT much different? Looks to me like I was running a LOT hotter plugs than I ought to have.

What do you think?

 

If they're shorter than the delcos, they are a colder plug, which would make you run rich. I had some autolites that a guy gave me and I fouled them in under 100 miles. I put them next to the stock replacements, they were 3/8-1/4" shorter than stock. Stock L98s and LB9s ran a very hot plug.

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The IROC Homepage
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View the restoration of an 85 IROC</A>
"I didn't know a bored out Ford could go so slow" -Shenandoah

 

See if this helps you any. Without seeing the plug personally I would hate to say anything.

http://www.centuryperformance.com/spark.htm

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88 IROC convertible
So slow it is timed with a sundial

 

My plugs looked most like the "carbon fouled" picture. That would be consistant with them being too cold. Thanks! Hopefully my new hotter ones will clear that up.

 

And, going with the notion that there is no such thing as too much information, here's another gob of information on spark plug reading.
http://www.strappe.com/plugs.html