Spark plugs

[Marcus Krueger]

ACDelco Professional Iridium Spark Plugs
I have a set of these from GM pn 41-985 .04 gap
should I use them in my 4.3 litre 1999 Safari This plug is not the recomended plug for this engine ...why?? any body know..
AC delco blurb.


ACDelco’s new Iridium Spark Plugs are the latest evolution in high-performance plugs. The natural properties of iridium, with a melting point approximately 700 degrees Celsius higher than platinum, enable the plug to burn fuel more efficiently and deliver better performance. As a result, the iridium plugs have a minimum service life of 100,000 miles.

Because it is one of the densest materials found on earth, the iridium-tipped center electrode is 50 percent the size of a platinum electrode and 20 percent the size of a conventional nickel electrode.

The secondary microdischarge of the center electrode burns off carbon deposits as they form for superior antifouling performance that, along with the tapered cut ground electrode, offers enhanced flame spread during combustion.

The specially designed electrodes increase the electric field strength at the gap, reducing the voltage required for sparking to begin, for improved cold starting and quicker acceleration.

The application coverage of ACDelco Iridium Spark Plugs continues to grow, with the plugs backed by a 100,000-mile Limited Warranty