Spark Plugs and wires?

[richtazz]

It's funny Bob, because when Delco changed from their old alpha-numeric system for plugs (ex-R44LTSM), it was easy to decipher because each letter means something. When they changed to the current 41-XXX system, they no longer gave heat range info. It's like GM engineers think we end users are too stupid to tinker with heat ranges for optimal performance. That list above is nice information. I also believe it is a misconception that platinum plugs retain heat and cause knock. The knock is caused by the heat range of the factory plugs, not the platinum/iridium tips. The two advantages to platinum/iridium plugs is they don't erode as fast and are self cleaning. As you stated, the advantage of copper core plugs are their price, especially if you change them often for tuning purposes. You can have 2 sets of 2 different heat ranges of non-platinum plugs for little more than the price of 1 set of platinums.

[SUERED]

Just had a similar discussion with coworker today. He told me he would not wait for what the book says----with long service over time these days, you run the risk of having a seized plug there. Meaning stripping the threads while attempting to remove it. Make sure you remove these on a stone cold engine by the way--as a placard on our GP states. Sounds like you have the original plugs on an 8 year old car? Over the Thanksgiving holiday I did plugs on our Ford V6--I had last done them 7 years ago. One plug really crunched when I began turning it ---believe me I was relieved when it came out fine. First time a plug ever "crunched" on me in 30 some years. I thought I had taken the threads with it. Whew!
JR