Spark Plugs

[Rick62]

Does anyone have any idea what causes a spark plug to look like this? It's from the 440 in my truck. Several others look like this one. Generally the porcelain is very white. However it has a black streak on one side.

 

[69a100]

It's kinda hard to tell from the lighting and a lack of description of what's on there, but I'll go with oil deposits along with burning rich. But wait and see what others say.

 

[dvw]

I see no oil there. Unless this was a full throttle hit, then the engine shut off and the plug pulled the reading is useless. You'll be seeing idle fuel.
Doug

 

[Vermont Rock]

It can sometimes be as simple as that section of the plug was facing away from the combustion chamber & was shrouded from the full force of the flame. It think it looks good. No oil. Light tan center electrode.
I spoke with both Champion & Autolite about plug readings & they both said that the only accurate visual reading can be seen near the base of the ceramic.