So I replaced my spark plugs today. First time in my Jeep and only the 2nd time I have ever done it in my own vehicle, so I have a couple of questions. The plugs I pulled out were AC Delco 41-631 and I replaced them with Champion Copper Plus. The picture I included shows the old plugs, based on the picture in the Haynes Manual, they look to be properly worn, do you agree? 2nd, are the AC Delcos decent plugs in comparison to the Champions? And 3rd, I measured the gap on the old plugs coming out and of the 6 only one measured .035, all the rest measured .030, so I ask how important is the accuracy of the gap? And will I notice any increased mileage from swapping to these new plugs with a proper gap?

 

Maybe a touch better mileage nothing to write home about, idle quality should be a bit better etc.Always check the gap and gap at factory settings unless other wise noted.