Reviews of AC DELCO spark plug

Believe it or not I got the Genuine AC Delco iridiums from Home Depot for $3 a plug.

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.

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.

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.

I had the same experience and ended up getting a code. Swapped them out back to AC Delco and never had an issue.

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.

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.

I just put in regular AC Delco plugs and it runs great.

Fresh AC Delco copper core plugs are all you need. Start with the stock replacements and go from there.

I just replaced my spark plugs on my 2012 1.4T with the ACDelco 41-121 ones.