Spark Plug Gap for 93 Performance Tuned 2015 GT?

[PaytonG]

What spark plug gap should I be doing? Also, any other tips for my first time replacing the spark plugs and coil packs?

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[RAVAGE88]

This is from the service manual. I gapped mine to .051.

The pax side rear cyl will be the toughest one to deal with, but overall, it’s an easy process.

MB

 

[K4fxd]

I like .040. I've seen dyno tests that say this is the best gap.

 

[WildHorse]

What spark plug gap should I be doing? Also, any other tips for my first time replacing the spark plugs and coil packs?

to factory spec. Nothing special to do them other then the 18+ decided to use a lead on the #3, like, couldn't find another spot for that DFI pump ?

 

[ice445]

to factory spec. Nothing special to do them other then the 18+ decided to use a lead on the #3, like, couldn't find another spot for that DFI pump ?

That one is easy, #4 is the most annoying lol

 

[WildHorse]

That one is easy, #4 is the most annoying lol

not talking difficulty, it's just a stupid spot for the pump.
as for #4, just use an extension with a u-joint on it.
Easy peasy.

 

[GregO]

I like .040. I've seen dyno tests that say this is the best gap.

It is interesting that the GT500 and Roush are just a touch under that .040” gap.

 

[tdstuart]

Do stock or a little tighter unless you are running into misfire issues. Had some random misfire issues and tightened gap to like .025 and it fixed it but this was with a higher compression motor on e85

 

[RAVAGE88]

It is interesting that the GT500 and Roush are just a touch under that .040” gap.

Boosted engines are typically gapped smaller than NA engines. All things being normal (pump gas, NA, etc.), best to stick with the factory settings.

MB

 

[RAVAGE88]

What spark plug gap should I be doing? Also, any other tips for my first time replacing the spark plugs and coil packs?

Meant to include, torque to 127 in lbs, use a dab of anti-sieze.

MB

 

[robvas]

Do stock or a little tighter unless you are running into misfire issues. Had some random misfire issues and tightened gap to like .025 and it fixed it but this was with a higher compression motor on e85

Have never had to gap a plug that tight without 15lbs of boost being involved

 

[K4fxd]

It is interesting that the GT500 and Roush are just a touch under that .040” gap.

I think that is for erosion over the life of the plug.

Another interesting thing is I have some papers that show .032 to .035 is best for emissions and fuel economy.

 

[tdstuart]

Have never had to gap a plug that tight without 15lbs of boost being involved

Ya not common and not sure why and if it was really the gap that was causing the misfire issue. Lund was the one that recommended it to me after I was having some random misfire codes at high rpm. Gapped it tight and they went away and motor was running strong.

 

[WildHorse]

Another interesting thing is I have some papers that show .032 to .035 is best for emissions and fuel economy.

I can see that with a conventional dizzy.. there's simply not enough time ( IMO ) to fire off any wider gaps. Even my old GM HEI I gapped them done to .035, much better than the .045-.050 called for.

But coil-on-plug is manmade lightning, so for NA the factory .050 is more than good.

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