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spark plugs: acdelco vs ngk

15112 Views 17 Replies 4 Participants Last post by  josh2012eco
Well, I think it's finally time to change the stock ngk iridiums that came in her at 96k.
Starting to get bad timing pulls under load like the copper plugs I had in after 5k miles (put the stockers back in and it went away).
So they have around 90k on them.
My question is: has anybody compared the ac delco iriduims to the ngk's?
I was going to go with the ngk($10ea), then I saw the ac delco's are $6 each...
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The AC-Delco 41-121 are the NGK 6 heat range OEM plugs. The 41-122 are the NGK 7 heat range OEM plugs. Which copper plugs did you try. I've had good experience (other than longevity) with the NGK vPower BRK7E and I just finished my first full day with the NGK BRK8E plugs. I've also had the NGK OEM plugs (AC Delco 41-122) and the NGK BRK7IEX iridium plugs and the BRK8Es are by far the best plugs I've had so far.
 

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The AC-Delco 41-121 are the NGK 8 heat range OEM plugs. The 41-122 are the NGK 7 heat range OEM plugs. Which copper plugs did you try. I've had good experience (other than longevity) with the NGK vPower BRK7E and I just finished my first full day with the NGK BRK8E plugs. I've also had the NGK OEM plugs (AC Delco 41-122) and the NGK BRK7IEX iridium plugs and the BRK8Es are by far the best plugs I've had so far.
41-121 are 6 (hotter); 122 are 7 (colder)
 

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Discussion Starter · #4 ·
I tried either the v-power brk7e or 8e's, I dont remember.
Gapped them to oem spec (.28 or .028 whatever it was) and they lasted around 5k
I'm sure they would have been ok if I re-gapped them again, but that weakens the electrode, so I said f it and put the stockers back.
I liked then gain, but I dont want to have to pull them out every oil change and service them.
I think I might try the 122's since they are a step hotter than the stockers and see if thats the sweet spot between copper and longer gap integrity.
Anybody know what they are putting in the '14's?
 

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Discussion Starter · #5 ·
On a side note, what's everybody's difference between the dic fuel used and pump gal. filled.
My car says 13gal, but the pump will say 14gal., a gallon off pretty much consistently over the course of a whole tank of gas.
 

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I tried either the v-power brk7e or 8e's, I dont remember.
Gapped them to oem spec (.28 or .028 whatever it was) and they lasted around 5k
I'm sure they would have been ok if I re-gapped them again, but that weakens the electrode, so I said f it and put the stockers back.
I liked then gain, but I dont want to have to pull them out every oil change and service them.
I think I might try the 122's since they are a step hotter than the stockers and see if thats the sweet spot between copper and longer gap integrity.
Anybody know what they are putting in the '14's?
I think they changed the part number again, and then went back to a 6? I can't keep track anymore. I have no idea why they keep going back and forth either.

Hotter will lead to more timing pull and low RPM pre-ignition, the very thing you want to avoid. Stick with a 7 heat range in the 1.4.
 

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My car seems to like the colder plugs better. It really seems to depend on driving environment.
 

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Discussion Starter · #11 ·
So, the 121's are colder than the 122's.
Cruze came factory with the ngk's which are equal to the 121's.
But the coppers I put in were the bkr7e's (found em in the garage) which are hotter than the stock ngk's helped get rid of the low rpm timing pull and bogging - how is this? They should have theoretically made it worse if I read these posts correctly...
 

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Discussion Starter · #13 ·
So the 122 should give be the same results as the coppers, but not wear the gap out every 5k miles, right?
This thing is getting a little more sluggish every day it seems.
Dirfferent jobsite has me going up 2 big ass mountains twice a day, feels like I'm running 87 but I'm running 93 since I started noticing a drop in power.
What normally takes 5th to get over now takes 4th, it sucks lol
 

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So the 122 should give be the same results as the coppers, but not wear the gap out every 5k miles, right?
This thing is getting a little more sluggish every day it seems.
Dirfferent jobsite has me going up 2 big ass mountains twice a day, feels like I'm running 87 but I'm running 93 since I started noticing a drop in power.
What normally takes 5th to get over now takes 4th, it sucks lol
Theoretically they are the same heat range as the copper plugs I initially made the recommendation for.

But apparently the long life IFR6/IFR7 plugs (121/122) are just a terrible match for this car. They are designed for long life and not much in the way of performance.

Give the BKR7E-IX-2667 (122 equivalent, still an iridium plug, shouldn't experience the gap erosion nearly as quickly, but also a higher performance iridium plug) or BKR8EIX plugs a try for your purposes. I still have not seen any instances of the "8" heat range fouling, but that is a possibility. So far, people have nothing but good things to say about those though.
 
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