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Old Oct 22, 2007 | 03:43 PM
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Default Spark Plug Gap

Iridium spark plug gap for c5 corvette / 50, 55, or 60?
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Old Oct 22, 2007 | 04:33 PM
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gm says .040 on Iridium. Others people will say.055-.060
If you buy ACDelco they should be pre gapped
doesn't hurt to check
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Old Oct 22, 2007 | 05:06 PM
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The AC Delco Irridium plugs (part number 41-985) come CORRECTLY gapped at .040 inches.
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Old Oct 22, 2007 | 05:18 PM
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Originally Posted by BlackZ06
The AC Delco Irridium plugs (part number 41-985) come CORRECTLY gapped at .040 inches.
Yep..
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Old Oct 22, 2007 | 06:08 PM
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It says not to regap plug.
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Old Oct 22, 2007 | 08:19 PM
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we were taught to always regap plugs, or at least check them. Think about the ups guy just tossing those boxes around during shipping. Do you think they are always going to land safely gap up? Where are they made? they have to get cross country or world somehow.
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Old Oct 22, 2007 | 08:24 PM
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Originally Posted by Z28TOZO6
Think about the ups guy just tossing those boxes around during shipping. Do you think they are always going to land safely gap up?
There is a cardboard piece that protects the gap end of the plug.
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Old Oct 23, 2007 | 06:34 AM
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Originally Posted by 2000C-5
There is a cardboard piece that protects the gap end of the plug.
take a new plug still in its box and drop it on a hard surface on its gap end a half dozen times. Then measure the gap. Keep in mind how much a case of 50 or 60 plugs weigh in a shipping box and think about how many times they are dropped on to pallets and in and out of trucks. I hope the cardboard is about an inch thick.
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Old Oct 23, 2007 | 08:45 AM
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Originally Posted by Z28TOZO6
we were taught to always regap plugs, or at least check them. Think about the ups guy just tossing those boxes around during shipping. Do you think they are always going to land safely gap up? Where are they made? they have to get cross country or world somehow.
You are right. The 30 seconds it takes to check the gap is nothing compared to pulling out all the new plugs looking for a miss. While checking the gap on more than one occasion I have found a defective ground strap. The plugs looked ok but the ground strap moved easily due to a poor weld between the strap and plug body.
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Old Oct 23, 2007 | 08:10 PM
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, I bought a set of iridium plugs for my sister's c5 a few months back and finally had some time this past weekend to swap them out along with a new set of GM wires. I never bothered to check the forum to verify the proper gap for the plugs. I just checked in the car's manual and it said to gap it at .060" which I did. Now I see that these plugs actually comes pregapped at .040".

The car starts and runs fine. It was a PITA to do the plugs. Should I be concern at all with leaving the gap at .060"? It's a daily driver and she drives like a grandma . TIA.
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Old Oct 23, 2007 | 09:35 PM
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If the car is running OK, I'd leave it alone. By altering the gap (which the AC Delco web site warns you not to do) you run the risk of two things ...

1) Breaking off the electrode while trying to regap them (which apparently you avoided ... )

2) Reducing the life of the plugs. They will probably start to cause a miss sooner than if they were at .040 .... maybe you'll get 50k miles instead of 100k miles out of them ... maybe 40k ... maybe 60k .... hard to say.

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Old Jan 12, 2008 | 01:21 AM
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I just picked up my Delco 41-985's, I'll check the gap but I'm looking for .040?
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Old Jan 12, 2008 | 04:01 AM
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I've been running a .035 gap for about three years, but I am blown and don't use Delco.
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Old Jan 12, 2008 | 06:53 AM
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Originally Posted by FUN LS1
I just picked up my Delco 41-985's, I'll check the gap but I'm looking for .040?
Yup .... 0.040 ....
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