Spark Plugs and Gap for 6.0 GMC

Sep 18, 2018
Kern Co. California

If this has been discussed here previously, I apologize for the repetitive post. I have a '03 GMC Sierra 1500HD with the 6.0L. I was replacing spark plugs on it and what I pulled out was AC Delco 41-110 gapped to (and the owners manual agrees) to 0.060". These are iridium plugs I believe. I was given AC Delco 41-962 double platinum gapped at 0.040". I found some information saying GM "updated" things and this is the acceptable replacement and new gap for it. I have heard due to the delicacy of the plugs, not to change the gap, but I did anyway. It ran good with the larger gap so it seemed reasonable to leave it that way. I used the tool that bends the ground strap and did so very carefully. I do not believe any damage was caused. The truck seems to run good now as it should, the plugs were not that old and had low miles on them.

Did I do anything wrong changing the gap? Should I try to find the older 41-110 plugs and switch back? Am I overthinking this too much?

Thank you all.
You shoulda left them gapped as they came but at this point I'd leave it if you have no complaints with performance
I have these 41-110 Iridiums in an 07 6.0 and is supposed to be better than the platinums. I don't think iridiums are spec'd for the older models. I'd run them until you notice a problem.

Spark plugs.JPG
Post #10 here clinebarger cites the TSB
At the moment, I want to run them and see how it goes, but I also dont want the family with me towing the trailer when a problem happens. I kind of want to hunt down the old plugs (that come gapped to what the manual says) and replace them...
{snip} Am I overthinking this too much?

Thank you all.
So much this.

Run the Iridiums. They're better and the COPs can push plenty enough spark thru them.

The proper gap for the Iridiums would be better but I wouldn't revert to the old plats

The next time you have a casual Saturday available pull them and bend the ground strap back to .040" if it'll help you the meantime have a Coke and a smile :D