Originally Posted By: mechtech2
Sure, you can just screw them in.
It is best to check them and set them, though.
Best plug performance comes with the widest gap that will never misfire.
That .004"extra allows better in and out flow of gas, in addition to a bigger and hotter spark.
Are they double platinum tips? BEing a copper plug usually means the core is copper for heat dissipation. It is rarely on the tips.
Precious metal tipped plugs wear slowly.
Even a double platinum is likely to have a copper core, as well as a resistor. My understanding is that most standard plugs use some sort of alloy material that includes nickel and copper for the exposed portion of the center electrode. The ground electrode seems to always be nickel plated.
http://www.densoproducts.com/product.asp?productCategoryID=1
In my experience, spark plugs tolerances are usually something like 1.0-1.1 mm. There's almost always an allowed 0.1 mm range in most specs I've seen.
I'm not sure exactly how the gap is measured with some of the proprietary standard plugs on the market. NGK V-Power makes things a bit interesting. However - Denso's U-Groove can make things even more interesting when the ground electrode is uneven. It's a little bit further in the groove, although I suppose it's supposed to be measured from the closest point between the two electrodes.