Believe it or not I got the Genuine AC Delco iridiums from Home Depot for $3 a plug.
Pros: cheap, genuine
Reviews of AC DELCO spark plug
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Problem solved: I got a internally bad ac delco spark plug. Gap and everything was correct no cracks I could see literally just a bad plug.
Pros: problem solved
Cons: bad plug
Vehicle:
Chevrolet Corvette
Problem solved: I got a internally bad ac delco spark plug. Gap and everything was correct no cracks I could see literally just a bad plug.
Pros: problem solved, gap correct
Cons: internally bad
I bought eight new AC/Delco from eBay. While gapping the plugs, I noticed that in two of them, the ceramic was not concentric with the body of the plug. It's difficult to measure, but it's easy to see by eye. I'd estimate the error is about 0.02 to 0.03 inches.
Cons: ceramic not concentric
Vehicle:
Chevrolet Silverado
Mileage: 85000 km
I had the same experience and ended up getting a code. Swapped them out back to AC Delco and never had an issue.
Pros: no more code
Cons: caused a code
Use the AC Delco iridium original plugs. Many sites will only show the double platinum as a replacement but every time I've ever driven an engine with those in it, it pinged or idled rough and iridiums always fixed it.
Pros: iridiums always fixed it
Cons: pinged or idled rough
Over the years I’ve found that the factory recommended spark plugs typically work best. There are exceptions, but my ‘95 5.7 recently got some plain Jane ACDelco plugs and it is running great.
Pros: running great
I just put in regular AC Delco plugs and it runs great.
Pros: runs great
Fresh AC Delco copper core plugs are all you need. Start with the stock replacements and go from there.
Pros: fresh plugs are all
I just replaced my spark plugs on my 2012 1.4T with the ACDelco 41-121 ones.
Part number: 41-121
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What we know about AC DELCO spark plug
The brand is registered in USA. Official website: http://www.acdelco.com/.
In March 2026, PartReview users have a mixed opinion of AC DELCO spark plug.
PR Score — 68 out of 100, based on 44 reviews and 137 votes. 28 positive reviews, 5 neutral reviews, 11 negative reviews. Average rating — 3.6 (out of 5). Vote balance: 94 up, 43 down.
In the ranking of the best spark plug this part is at position 7, behind OEM Mazda and OEM Volkswagen , but ahead of OEM Toyota and Motorcraft.
Users also evaluated the qualities of AC DELCO spark plug:
- Starting - cold starts are difficult - rated positively. 4 points out of 5.
- Idle - engine shakes and runs unevenly at idle - rated ambivalently. 3.1 points out of 5.
- Acceleration - hesitation or stumbling when speeding up - rated positively. 3.6 points out of 5.
Spark plug AC DELCO in car-specific ratings
See which car brands and models owners choose AC DELCO spark plug for. Below are car-specific ratings where this part is in the Top-3:
- AC DELCO ranked #1 in spark plug ratings for: Chevrolet Cruze .
Spark plug AC DELCO in comparisons
There are 16 comparisons of AC DELCO spark plug with other manufacturers on PartReview.
In particular, see which spark plug are better: AC DELCO or OEM Mazda, AC DELCO or OEM Honda, AC DELCO or OEM Audi, AC DELCO or OEM Subaru, OEM BMW or AC DELCO .