I just purchased a set of NGK iridium ix tr55's...It says they are pre-gapped to 40..sounded weird to me, I've always gapped my tr55's around 50-55..I tried a search on this before asking, but the search engine is acting up...funny how it always seems to do that...Any help is appreciated...

 

I would also love a definite answer to this question. These plugs are sitting in a pretty significant parts pile at home, waiting for me to get home from Iraq. They will be going in along with a ported throttle body, LS6 intake, TR224 cam, long tubes, and a whole mess of other supporting parts. I would hate to do all that work and have my $7 a peice spark plugs causing me problems cause they are not gapped correctly.

 

gap tr55's at .050-.055


.040 is more for the TR6 light blown/nitrous users

 

So just because they are iridium plus, it should not make any difference, right? Has anyone heard of having problems using the iridium plugs?

 

I've had both the Denso IR-16s which are like the TR-55IX's and now TR-55IX's and have never had any trouble. I checked the gap to ensure .55 on all plugs and they work fine.

The Denso IR-16s are $15 per plug so be glad you have the NGKs.

 

Thanks for the reply. I will gap them at .055" and go with it.