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Iridium Spark Plug Question

2K views 5 replies 5 participants last post by  T0rque 
#1 ·
I have a stock 04 WRX and am replacing the spark plugs in the next few days. I have been given 3 different options for plugs; regular NGK's, platinum NGK's, or Denso Iridium's. the Denso's i bought say 0.4mm. Can you gap iridium plugs or are the pre set? .4mm seems a little big of a gap to me and I'm debating on just having the platinum's ordered instead.

the first plugs I bought were the NGK's for the 2.5 non turbo...would those have hurt my engine?
 
#2 · (Edited)
You asked whether iridium plugs can be gapped. I'm not going to answer that. Instead I'll answer whether iridium plugs should be gapped. That answer is no. NGK state this outright in their info material on the iridium products. They also state that there is no warranty on damaged iridium electrodes.
http://www.ngk.com/glossary.asp?kw=Should+I+gap+my+Iridium+Plugs?&manID=1&pt=

If you want to gap them you might try this method:
http://www.ngk.com/glossary.asp?kw=Proper Gapping&pt=1

Denso state that their iridium product compensates {sic} for smaller gaps that correspond to other plugs, i.e. platinum.
 
#3 ·
I did the iridiums and didn't gap them cuz they said not to and it runs amazing
 
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