AC Delco plugs

[SuperBuickGuy]

boy is it rare when I call a company out by name - but given the cost and aggravation. It's time. Never, ever buy AC delco spark plugs. Whether unobtainium or their copper core, the housings crack and will cause you no end to trouble. I just replaced plugs on my H3 Hummer, one was bad. It ate 3 coils before I finally figured out what was going on - easy crack to see (bastards). Follow this up, I have an FJ40 with a 350 chevy in it. I kept going through ignition modules. 5 of 8 plugs are cracked. The H3, the plug was brand new. The FJ40, 1000 miles.... run away from them, they want to save money making that stuff in China - why should I have to bear their R&D and quality testing?

[Barry Donovan]

the vortec shipped with platinums... it ate them like candy. my own gapped to .080 and kept running.

I then found iridiums.. ac delco.
I open the package and see "1995".
I stil wonder if they invented them.. and did not make enough for their own production line.

I ponder they get ahead of themselves. try a different ac delco, long story short.
My truck is working wonders.

you got something feisty to crack plugs. Wrong heat number or something.

[squirrel]

they last changed the artwork on the box in 1995.

AC plugs work fine for me. I guess I have the knack.

[anotheridiot]

only have cracked champions in my time. Moved from E3 back to NGK just because the other suggested plug for the aluminum heads were Autolite and I wont put ford parts in my chevy

[silver_bullet]

We use AC Delco irridium only...

[SuperBuickGuy]

one was an iridium .... pictures
all 8 from the FJ40 - they have 1000 miles on them.... what's really cute is that one of those is covered in carbon, like it wasn't firing, and that one isn't one of the cracked ones...






these 5 all have something wrong with them

[malc]

I went to Autolites years ago..

[Runner1972]

Still running 41-906 plugs in the SS we never had an issue. I'm running Accel Shorty header plugs in the 72 that were made in Japan, last box i seen they are made in Russia now I think

[JOES66FURY]

Never had a problem with Autolites...

[Jim Rockford]

NGK all the way in everything I own..

[tomicdesu]

hmm... i've never had a plug fail itself, in 40 years of car wrenching and doing lots of stupid things to engines. i've ruined plugs for sure, fouled, overheated, dropped, over or under torqued, but i can't honestly say i've had a plug fail all by itself. in the past id shopped by price, or just got what the store had (crappy old Champions usually). Now i tend to by Japanese plugs, mostly because i can get the odd sized plugs i have in a few heat ranges.

if all plugs but one look OK, the first thing i'd do is at least a simple compression check of all cylinders and figure out why that one is different. it's a good idea to do that every couple years or when you're in there like this, and write it down somewhere (inside cover of the service manual for the car or whatever) so when s**t hits fan later (lol, now) you have a baseline.

if the plug condition are not even, then there's something wrong. some inlines have lean at the end cyls, that's less of a big deal.

black and dry-fluffy is often misfiring; black and sticky/shiny is oil. pretty much any chunky buildup on plugs today is from oil ash.

and these days, gasoline chemistry is very different than the past, it leaves almost no residue! i usedta tune by plug color, that doesn't work the same as it used to with pump gas. at the moment i'm running rich (12:1 to 13:1) on the wideband AFR meter in the dash, and the plugs are still white white.

[Dan Barlow]

Humm . We've blown three of the 6 coils in the trailblazer .I changed the plug a while back . I replaced the coils with used ones from the junk yard since Delphi ones are about$100 bucks each, and the have had good luck with each one . Well it started running on 5 of 6 again so I ordered 6 coils off the internet where I can get 6 for the price of one .I'm going to check the plugs .

[SuperBuickGuy]

plugs - that cost me 3 coils on my H3

[68scott385]

I had a bad AC Delco plug right out of the box about 12 years ago. It was for my wife's van. I did a tune up (mid-90s GM, cap, rotor, plugs & wires) the day before we left for vacation. What should have been a 19mpg vehicle turned into a 12mpg vehicle. I wound up changing plugs in the rain in the hotel parking lot. I let them have one anomaly, six sigma right?