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3100 V6 Spark Plug Gap


94GrandPrix

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The owner's manual states that a .060 spark plug gap is recommended, but would it hurt/change anything if I use a .045 gap instead?

 

If anyone asks why the .045 gap, it's what the spark plugs I'm planning on buying are pre-gapped to :P

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It will probably run like shit. Why would you want .045? The ignition system on the GM V6s is one of the best ones out there from my understanding compared to other make/models out there. What spark plugs are you planning to use?

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It will probably run like shit. Why would you want .045? The ignition system on the GM V6s is one of the best ones out there from my understanding compared to other make/models out there. What spark plugs are you planning to use?

 

Like I said, why the .045 gap? It's the pre-gap on the AC Delco plugs I was looking at.

 

Guess that's why they recommend .060 in the owners manual right?

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i'm pretty sure all almost all later model gm vehicles fall under a tsb for .045" gap, those should be fine, i gapped mine around .028-.030 and it runs perfectly fine for regular driving without boost.

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a gap too small is preferable to a gap that is too big. too small might run oddly, but too large will fail to spark at high load, which does really interesting(bad) things to your secondary ignition, along with falsely triggering the knock sensor most of the time.

 

that being said, a 3100 can run .080 and still not misfire under heavy load, especially with platinum/iridium plugs.

 

I would just gap them to the correct spec and be done with it.

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I ran 0.06 for a few years and found that it was very hard to start in the winter. Practically impossible below -25C. Removing the plugs and re-gapping to 0.045 resolved problems starting at those temperatures completely.

 

Intuitively this makes sense as the dielectric strength of air is improved with decreased temperature.

 

Also, since re-gapping, high load low-RPM misfires disappeared. Anecdotally I believe the fuel efficiency decreased slightly, but I haven't taken it on a good 400-500 mile trip yet to definitely prove this.

 

The manufacturer specified gap is printed on a sticker underneath the hood. IMHO, this should be obeyed unless there's a really good reason to want something different.

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