What's with this spark plug? .... carbon at base of threads...pics
 

Here is a pick of my spark plug. The electrode components came out nice and brownish-white, like I understand they're suppose to. However, several have flakey black carbon at the very bottom of the last thread of the plug???

(Not on the insulator or the electrode)



http://forums.pelicanparts.com/uploa...1084068780.jpg

http://forums.pelicanparts.com/uploa...1084068852.jpg