# Not sure what the difference is but....



## Patman (May 7, 2011)

As I mentioned in a previous post I switched out a set of "AC Delco" labeled plugs to replace with the original NGKs that came out. The Delcos I took out were gapped at .028 and I gapped the the old NGKs at .030. even without the tune the car feels like it has new life and tuned again! I have a Trifecta perf tune and have been back and forth with it. When installed, the car seems to take off(turbo kicking in) more than not. I have installed and detuned the car 2 times so far and now with the plugs gapped at .030, it feels better than tuned. I somehow feel like I am slowly "killing my car and and any chances of decent "Eco MPG" (with this stupid tune that was told to be within specs) but I drive @95% city and I am looking at @ combined 33.5 I don't know maybe just paranoid but the car runs better with the plugs changed .030. See how well it runs now.


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## jblackburn (Apr 14, 2012)

41-122?


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## spacedout (Dec 7, 2010)

jblackburn said:


> 41-122?



I would love to know the difference between the different AC delco part numbers, is there a heat range difference? gonna be replacing mine soon probably with stock plugs, I see rockauto has a few part numbers listed. 

Off topic slightly, but I also noticed rockauto has different plugs listed depending on what year cruze you enter.... seemed strange since there has been no engine changes.


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## jblackburn (Apr 14, 2012)

spacedout said:


> I would love to know the difference between the different AC delco part numbers, is there a heat range difference? gonna be replacing mine soon probably with stock plugs, I see rockauto has a few part numbers listed.
> 
> Off topic slightly, but I also noticed rockauto has different plugs listed depending on what year cruze you enter.... seemed strange since there has been no engine changes.


They went from 6 (41-120) to 7 (41-121) heat range and I THINK back to 6 again for 122 (in NGK plugs, 6 is hotter). Not sure on the 122. Changed each year though - seems like their engineers realized there was a problem with preignition as well.


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## Patman (May 7, 2011)

I was thinking about the plugs I put back in my Eco and I think I may have put the NGKs I took out of my LS. What ever it is, they were coming up with the same AC Delco plug # and the car runs great so who cares. Maybe I should throw some of the old plugs out. I think I have a set of AC Delco 41-120 the 41-121 and the other set of NGKs(from either my LS or the Eco). The set not in the car duh!!!!!! Surprised no one mentioned the gap change from .028 to .030. I still feel the low end power I was missing with the old plugs(Kinda like tuning).


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## brian v (Dec 25, 2011)

What are you rambling about Dawg ? Now yer Eco runs better and ya can't figure out what plugs ya put in or if it is even tuned ! 

33 mpg city is phenominal , that is better than most hybrids today .


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