I changed my plugs and plug wires recently because my car was smoking (black smoke) when at high rpms (BTW, the car still smokes at high rpm). I am pretty sure these are the plugs from the factory. 133k miles.

How do they look?

 

The first one on the left shows signs of soot from too much fuel or engine oil. The other three look like they were running too hot. (Are they the correct heat range for your application?) Gap looks excessive, but they are pretty well worn.

Just my uneducated opinions. FWIW, I like to see mine have a slight hint of tan on the ends. Also, what's all the black stuff on number 3's insulator?

 

Very hard to tell by looking at a pix, but these may help... http://www.verrill.com/moto/sellingg...colorchart.htm

http://www.griffinasher.com/Spark_Pl...s_catalog.html

http://www.hioutput.com/tech/plug.html 94