C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Spark Plug Gap for Iridium Plugs

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Old Jun 2, 2003 | 04:17 PM
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Default Spark Plug Gap for Iridium Plugs

Getting set up for the dreaded spark plug / wire replacement this weekend. Just a couple of questions, having never done this on a Vette before.

Gap - .050 sound correct for the NGK Iridium Plugs? I plan on using the Taylor Spiro 8mm wires.

Are there any special tools or tricks I need to make the job easier? I understand #8 can be difficult.

As always, thanks in advance for the assistance. :cheers:


[Modified by Da Wiz, 9:19 PM 6/2/2003]
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Old Jun 2, 2003 | 04:20 PM
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Default Re: Spark Plug Gap for Iridium Plugs (Da Wiz)

I didn't gap my Iridium, they looked to fragile. The car runs really smooth with their factory gap settings.
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Old Jun 2, 2003 | 04:22 PM
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Default Re: Spark Plug Gap for Iridium Plugs (Da Wiz)

Tip: for #8, I used a spark plug socket and an open end wrench to turn it.
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Old Jun 2, 2003 | 04:41 PM
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Default Re: Spark Plug Gap for Iridium Plugs (Da Wiz)

On my 92 I like to remove the ft wheels and wheel wells(middle and rears) makes the job a "LOT" easer, with a extenstion and swivel #8 no problem.
I think .050 is factory on the Iridiums.
:seeya :flag


[Modified by C4Crazy787, 4:44 PM 6/2/2003]
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Old Jun 2, 2003 | 05:10 PM
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Default Re: Spark Plug Gap for Iridium Plugs (C4Crazy787)

Thank you Gentlemen,

Your kindness is exceeded only by your wisdom (and scarred nuckles ).

I am glad no horror stories have surfaced....oops, was that out loud?

:cheers:
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Old Jun 2, 2003 | 06:21 PM
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Default Re: Spark Plug Gap for Iridium Plugs (Da Wiz)

Got a '92 myself. GM shop manual says .050" for Vin P motor (LT-1) .035" for Vin J motor (LT-5)
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Old Jun 2, 2003 | 06:44 PM
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Default Re: Spark Plug Gap for Iridium Plugs (Da Wiz)

As vvv90 said, gap should be .050. My NGK TR55ix's checked at about .054 out of the box and thats where I left them. So far so good.

You will not regret the iridium's. In my car, they seemed to yield a slight increase in throttle response over the new (6000 miles on them) stock AC 41-906's that I was running. Plus, with the new taylor wires, they ought to really work out well for you.
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Old Jun 2, 2003 | 07:30 PM
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Default Re: Spark Plug Gap for Iridium Plugs (Da Wiz)

Mine came somewhere around .055-.059. Debated for a while and decided to back 'em down to .050. Very nice plug, I really like them.
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Old Jun 2, 2003 | 07:33 PM
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Default Re: Spark Plug Gap for Iridium Plugs (Da Wiz)

I fouled out 2 sets of NGK TR55 Iridium plugs (wasting $90) when my O2 sensor went bad. It left me first with a no-start condition, and then after replacing the plugs, ran for 30 miles, and then left me walking on the highway.


The problem was my O2 sensor, but I was told normal plugs, would not have fouled so quickly.

All I am saying is they are more susceptible to fouling.
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Old Jun 3, 2003 | 12:02 AM
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Default Re: Spark Plug Gap for Iridium Plugs (dizwiz24)

Thanks for the input fellas. Sorry you had the problem DizWiz.

I changed my mind regarding the Taylor wires. I decided to go with the 8mm Magnecores. Read a lot of good things about them, specifically regarding noise suppression and durability along with some pretty impressive resistance data. Couldn't find a vendor, so I contacted the company and they took my order over the phone. They are supposed to arrive around Thursday. They were very close in price to the Taylor wires, with only 4 bucks for shipping. Total price is @82 samolians.

Thanks for all the info. Anyone have any idea what "heat range" the Iridiums are supposed to be in? Kind of irrelevant, since they only make one plug for my car, just random musings....

:cheers:
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