Originally Posted by crashman
I'm a big fan of the NGK iridiums. However, if your 104's have 10K miles, then even putting a new set of 104's should be beneficial.
The Iridiums aren't really suppoed to be gapped. Two reasons. First ist easy to break the center electrode and the iriduim coating is very thin. I would imagine even if you didn't accidently damage the center electrode, you would still want to be careful not to scuff the center electrode tip and rub the iriduim off.
The TR55IX plugs are a stock replacement and gapped at .060 (stock gap). The TR6IX are gapped at .039, which means you would have to gap them.
What I did was used two flat blade feeler gauges to create the .055 gap I needed. They were stacked like this -_ I put the bottom gauge blade on the center electrode and ONLY slid the top blade for checking the gap -_ to = and back to this -_ when removing. You can gap them, but you just have to be careful. And never attempt to gap these plugs with a wire gauge or circular step disk gauge.
