I am not mechanically inclined, so don't get upset at me for asking what may seem like a very simple question to you. When pulling your plugs and looking at them, how would you know, or what are the tell tail signs that they are bad or need to be replaced? Thanks.

I am not mechanically inclined, so don't get upset at me for asking what may seem like a very simple question to you. When pulling your plugs and looking at them, how would you know, or what are the tell tail signs that they are bad or need to be replaced? Thanks.

They should look clean, maybe a little whitish. If they are black with carbon, time for some new ones. Also look at the electrode (rod in center) if it is wore down, time to replace.

http://i143.photobucket.com/albums/r147/hdwayback/spark_plug4.jpg

http://i143.photobucket.com/albums/r147/hdwayback/WornSparkPlug.jpg

they should be a brownish color ,show no wear. if they are black and sooty it indicates a rich fuel or poor ignition, if they are oily, the rings or valve seals are leaking , if white and blistered , they are too high heat range, if the tip is melted its an indication of preignition or detonation,

Dont be afraid to go down a heat range from what the factory calls for. I did and my 90 L98 seems to run cooler as well