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post #1 of 7 Old 08-04-2005, 08:55 PM Thread Starter
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spark plug gap

I have a 2000 xj 4.0 and the spark plug gap is .35 now i have herd some fellas increase the gap to .40 and said there Jeeps runs as good or better. Is this true, and have any of you guys tried it.

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post #2 of 7 Old 08-04-2005, 09:37 PM
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It's probably true but you'll need to replace them a little more often.

2001 Grand Cherokee Limited. 4.7 V8, Quadradrive, Tow Package
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post #3 of 7 Old 08-04-2005, 10:10 PM
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ummmm.... .035, and yes .040 works well, .045 works nice too, but it eats plugs up
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post #4 of 7 Old 08-04-2005, 11:49 PM
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This was helpful to me as i had the same question. Hope it helps.
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post #5 of 7 Old 08-01-2009, 06:23 PM
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I find this interesting because I just changed my plugs; the last set were installed at a shop, and I did them myself this time to save money.

.035 gapped plugs went in (as specified), but the ones that came out (installed years back by a shop) were gapped at .050 ...

Any ideas how that larger gap would have affected performance? Jeep ran OK, but mileage wasn't all that great ...

I have to wonder if it's been running incorrectly gapped plugs all this time, or if they've just worn out to the point the gap is now that large.

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post #6 of 7 Old 08-01-2009, 06:46 PM
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Originally Posted by _litz View Post
I have to wonder if it's been running incorrectly gapped plugs all this time, or if they've just worn out to the point the gap is now that large.
With conventional plugs, you could expect that type of gap increase in 25-30k miles.
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post #7 of 7 Old 08-01-2009, 07:04 PM
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I jut changed my plugs the other day and they were gapped at .70, i was still getting 19 miles per gallon and had good power. they must of never been changed my jeep only has 90,000 on it.

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