Plug gap? .035 .040. or.060? Which and why?
Plug gap? .035 .040. or.060? Which and why? Ok, I changed my stock plugs out and installed some new ones that are not platnum. I gapped them to .035 like the boys at NX suggested. The car idealed ruff with an inconsistant miss at idle. It ran great on the juice. Now I changed the plugs again but this time I set the gaps to the factory spec of .060 . Now the car idles nice and smooth like it did new. I have not tried the juice yet. I want to know if .060 gap is a bad thing on the juice. Why would I want my gap closer? What are the advantages and the disadvantages. I would like to keep the gaps at .060 but if there is some danger in it then I will destroy my arms again and change the gaps to a lower setting. Thanks guys. 
Re: Plug gap? .035 .040. or.060? Which and why? There are two concerns when considering plug and gap.
1) correct heat range- too hot of a plug will cause detonation due to the electrode becoming hot enough to light the fire before the spark. Detonation is an engine killer!
2) plug gap- if not correct the ignition system will be unable to provide a strong enough spark with the added resistance of a densely filled cylinder such as an N20 charge. This can result in misfires or even complete cylinders dropping out ...especially in higher rpms.
For your case I would use TR-6 gapped as they come out of the box. I think it was .038. You could probably increase that to .040-.042 if you want to improve the idle a bit.
1) correct heat range- too hot of a plug will cause detonation due to the electrode becoming hot enough to light the fire before the spark. Detonation is an engine killer!
2) plug gap- if not correct the ignition system will be unable to provide a strong enough spark with the added resistance of a densely filled cylinder such as an N20 charge. This can result in misfires or even complete cylinders dropping out ...especially in higher rpms.
For your case I would use TR-6 gapped as they come out of the box. I think it was .038. You could probably increase that to .040-.042 if you want to improve the idle a bit.
Re: Plug gap? .035 .040. or.060? Which and why? I did put the TR-6 in but I opened the gap to .060. I can close them a bit to .040. It sounds like to me the stock ignition system is not strong enough to lite off the NX mixture at high rpm. Would a good high power after market igniton make the plugs work right at .060? Is there even a good high power ignition system out on the market yet that will be easy to install? I will regap them to .040 as soon as I get back home. My poor arms 
they went through so much SH*T last week working on the passenger side plugs. I hait the tight quarters on the passenger side! Any pointers anyone to help save my arms? 
they went through so much SH*T last week working on the passenger side plugs. I hait the tight quarters on the passenger side! Any pointers anyone to help save my arms? 
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Joined: Nov 2001
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From: Troy, AL
Re: Plug gap? .035 .040. or.060? Which and why? The stock ignition system is not only strong, it's OVERKILL. .060 is an insanely wide gap and it's only becuase of this overkill ignition that .060 is even possible.
The general rule of thumb is to narrow the gap by .004 for every 50 HP you add.
TR-6s work great when gapped at about .038-.045. .060 is way to wide for them. According to NGK, you shouldn't stray more than .20 from the stock gap on any of their plugs. The stock gap of a TR-6 is supposed to be .039 (they should, however, be checked because they're not always .039 by the time the get to you.)
I would not run nitrous with the plugs gapped that wide. Put 'em on .038-.045 and they'll be fine with your 150 shot. BTW, I've always ran them at .038 and have never had an idle problem with them.
The general rule of thumb is to narrow the gap by .004 for every 50 HP you add.
TR-6s work great when gapped at about .038-.045. .060 is way to wide for them. According to NGK, you shouldn't stray more than .20 from the stock gap on any of their plugs. The stock gap of a TR-6 is supposed to be .039 (they should, however, be checked because they're not always .039 by the time the get to you.)
I would not run nitrous with the plugs gapped that wide. Put 'em on .038-.045 and they'll be fine with your 150 shot. BTW, I've always ran them at .038 and have never had an idle problem with them.
Re: Plug gap? .035 .040. or.060? Which and why? Thank you Colonel. When i had the .035 gap i was using Autolight plugs. I had to order the TR-6's. That was when it was idleing ruff. It just had an eratic miss that anoude me more then caused any problems. I did get a code for the bank 2 converter being out of wack. When I cleared it and installed the TR-6's with the .060 gaps it never gave me that code again. But I have yet to hit the juice either so I do not know if the code was do to the autolight plugs or from when I hit the Juice. When I get back home from offshore (I work in the Gulf Of Mexico for an eviel oil company) I am going to close the gap on those plugs to .038 like you say. Thanks for the help guys!!
Scott Graham
Scott Graham
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Re: Plug gap? .035 .040. or.060? Which and why? You get the strongest ignition "kernel" when you
have the gap at its widest. This is because coils
are current-mode output, you get (roughly) the
same current regardless of gap. But, the voltage
goes up with the gap distance, and more volts
times the same spark amps is more power / energy
hence a surer ignition.
But, the same voltage that will reliably jump a
.060" gap, barely, on a NA car may fail to spark
on a car with a bigger intake charge, because
higher gas pressure = higher breakdown field.
If the spark doesn't happen, it's like the old
Indian joke... left nut go Unhhh... rubber go
Unhhh... right nut go "Pow!". The coil energy
goes somewhere and if it isn't the plug, it's
coil arcing or breakdown in the coil switch.
That, and you don't fire the cylinder, which
cuts down on the fun.
have the gap at its widest. This is because coils
are current-mode output, you get (roughly) the
same current regardless of gap. But, the voltage
goes up with the gap distance, and more volts
times the same spark amps is more power / energy
hence a surer ignition.
But, the same voltage that will reliably jump a
.060" gap, barely, on a NA car may fail to spark
on a car with a bigger intake charge, because
higher gas pressure = higher breakdown field.
If the spark doesn't happen, it's like the old
Indian joke... left nut go Unhhh... rubber go
Unhhh... right nut go "Pow!". The coil energy
goes somewhere and if it isn't the plug, it's
coil arcing or breakdown in the coil switch.
That, and you don't fire the cylinder, which
cuts down on the fun.
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Too wide of a gap would be a good way to fry some coils. 
