Best Vortec head spark plugs for reliability and performance?

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PlayingWithTBI

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I went to the Accel "Header" plugs since they are shorter and use a 5/8" socket instead of 13/16" which made it a little easier to get them in without too much genuflecting. Now I wonder where they're made :cool:

Accel vs NGK with gasket seat for aluminum heads.
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L31MaxExpress

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AC hasn't made spark plugs in decades. Far as I know, they're bought-in from NGK. At least, some part numbers are NGKs with different markings, in an ACDelco box. I like NGK.

I was big on Autolites until they moved production to China.

My Trailblazer came with Iridium plugs. The originals lasted 160K miles, coming out at 90K--and they looked so perfect they went right back in, even though I'd already purchased a new set. I wouldn't put Iridium or Platinum plugs in a carbureted engine, or even a TBI. But for a port-injected OBD2 engine that doesn't have a history of oil consumption...sure.

Haven't bought a Champion plug in decades; I swore I'd never buy another Champion when I figured-out they had the most-brittle porcelain in the industry. Soft, fast-wearing electrodes, too.

Not real big on "gimmick" plugs, either. Splitfire, E3, the Bosch plugs with two or four ground electrodes...No, thank you.
My 07 G35 had NGK Iridiums. Still looked a lot better then I thought they would at 177K. Only changed them because I was doing the valve cover gaskets. The gap had grown from 0.044" to 0.051"

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SAATR

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Some kitty Cat spark plugs for your viewing pleasure and general befuddlement. Made in Germany. These have just a few hours on them and were out for inspection and diagnosis. The one on the far right was our problem cylinder, running a bit lean. You'll notice a hazy look on the dome compared to its counterparts. They're changed based on ignition secondary voltage rather than runtime, generally. Used in medium sized, lean-burn natural gas engines.

My Vortecs get 41-993's. Judging by the stamping and general construction, I agree that they are probably NGK's.
 

Caman96

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My Vortecs get 41-993's. Judging by the stamping and general construction, I agree that they are probably NGK's.
Copper =/= OEM with Vortec heads.
I’ve had the Iridium 41-993”s in for a couple of years, runs beautifully. They’re also manufactured in US unlike the China made R44LTS6. The R44LTS6’s just might be going back to the PRC!
Just re-checked: Acdelco Double Platinum, Iridium and Rapidfire(Gold) are all US made. Only the R44LTS6 is made in China.
 
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Supercharged111

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Some kitty Cat spark plugs for your viewing pleasure and general befuddlement. Made in Germany. These have just a few hours on them and were out for inspection and diagnosis. The one on the far right was our problem cylinder, running a bit lean. You'll notice a hazy look on the dome compared to its counterparts. They're changed based on ignition secondary voltage rather than runtime, generally. Used in medium sized, lean-burn natural gas engines.

My Vortecs get 41-993's. Judging by the stamping and general construction, I agree that they are probably NGK's.

You're gonna need to clarify kitty cat, because this is what comes to mind for me.

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95burban

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Some kitty Cat spark plugs for your viewing pleasure and general befuddlement. Made in Germany. These have just a few hours on them and were out for inspection and diagnosis. The one on the far right was our problem cylinder, running a bit lean. You'll notice a hazy look on the dome compared to its counterparts. They're changed based on ignition secondary voltage rather than runtime, generally. Used in medium sized, lean-burn natural gas engines.

My Vortecs get 41-993's. Judging by the stamping and general construction, I agree that they are probably NGK's.
Those plugs act as prechamber and produce a flame front to help combustion.

I run denso iridium’s in my 3500 and 3600 cats and champion coppers in the smaller ones.
 

SAATR

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Those plugs act as prechamber and produce a flame front to help combustion.

I run denso iridium’s in my 3500 and 3600 cats and champion coppers in the smaller ones.

Correct, as seen in the C/E/H model 3500's.

I work for a dealer, so the OE plugs are all I ever install. Given what they charge for a rebranded plug, I don't blame anybody for finding a good aftermarket equivalent.

I've gotten GE branded plugs in Cat boxes before. Funny, but tough to explain to the customer when you have to drive three hours roundtrip to get what SHOULD have been in the box in first place. Parts department didn't appreciate the bill, either.
 
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