should i close the gap??

rw98gt · Jul 27, 2008

i was wondering if i close the spark plug gap a bit would i get better fuel burning from my supercharged 4.6? i was reading a couple different articles on supercharged stangs and i noticed that they closed up the spark plug gap some, i am still running w/stock gap. would this help with producing more power and burn cleaner. i have noticed that the car runns a bit lean, i just replaced an o2 sensor and would like to burn clean. any advice would be greatly appreciated. thanks, ron

RedDaemon · Jul 27, 2008

arent you supposed to run cooler plugs anway?

blubullett · Jul 27, 2008

-=NightHawk=- said:
arent you supposed to run cooler plugs anway?

What does cooler plugs have to do with the gap anyways? I run ngk copper core gapped at .35 and it runs really clean. When I got my last smog check all the values were way at the bottom of the pollution scales.

darkside03gt · Jul 27, 2008

-=NightHawk=- said:
arent you supposed to run cooler plugs anway?

it depends on what whos supercharger you are running. vortech reccomends stock gaps and fresh plugs when you install the supercharger. but for guys who are really pushing it with more boost they need colder plugs. but i dont think adding them would hurt any aplication.

to the OP. you can decrease your gaps a little and it shouldnt hurt. i decreased mine by .006 or so with no issues. but that wont help you lean problem. do you have a wideband on your car? what the afr at ide? half throtle and WOT?

RedDaemon · Jul 27, 2008

blubullett said:
What does cooler plugs have to do with the gap anyways? I run ngk copper core gapped at .35 and it runs really clean. When I got my last smog check all the values were way at the bottom of the pollution scales.

dont they achieve the same basic results?

shortening the gap decreases burn time

cooler plugs allow for a decreased chance of pre-detonation

these both have a direct relationship on burning efficiency would they not?

you have your plugs gapped at .35 stock for a 99-04 i believe is .55 (i cant really remember) if you wanted to increase the gap enough to make a difference you would most likely have to run a cooler plug right?

my original point to the OP was that he should have done one of these to begin with

rw98gt · Jul 27, 2008

well when i installed the charger i did it myself, and i never read anything about changing the plugs. there was no mention of it in the manual(even though i put new 1's in about 6 month before the install). any recomendations on what plug to use and what i should gap it to. i'm running a cheapass powerdyne @6lbs but i have a 11lb pulley that i may swap in. i even had the car pro tuned and they made no mention of the plugs to me while tunning on the dyno.
i think they retarded my timing like 10degrees & told me if i hear any detonation go to 11 degrees. it sounds like an awfull lot of timing taken out for only 6lbs of boost.
i am still running stock injectors w/an inline boost pump. could this be my problem?
when i say detonation i hear it under full pedal (a very slight ping or rattling).

Tim2002GT · Jul 27, 2008

I would get some NGK TR6's and gap them to .035. They are commonly used on blower/nitrous cars. They are 1 heat range colder than stock.

BigDave06 · Jul 27, 2008

I am running NGK BR7EF's gapped .032 they're 2 steps colder.

blubullett · Jul 27, 2008

-=NightHawk=- said:
dont they achieve the same basic results?

shortening the gap decreases burn time

cooler plugs allow for a decreased chance of pre-detonation

these both have a direct relationship on burning efficiency would they not?

you have your plugs gapped at .35 stock for a 99-04 i believe is .55 (i cant really remember) if you wanted to increase the gap enough to make a difference you would most likely have to run a cooler plug right?

my original point to the OP was that he should have done one of these to begin with

I thought you read the post wrong or something, didnt get the point you were making. Procharger recomends a smaller gap and 2 heat ranges cooler than stock.

rw98gt · Jul 28, 2008

i just came accross a set of denso iridium spark plugs i had in my basement(i never used).
they read ULTRA FINE 0.4mm IRIDIUM U-GROOVE TAPPERED CUT
IT16#4
5325#4 125

does anyone now if these will work and if so should i gap them .032 or will i just have to buy some thing else like NGK's?

04GTMustang · Jul 28, 2008

all closing the gap really does is make it easier for the spark to jump under boost. for an NA car a wider gap is best but not too wide. .054 is good for NA. you can keep stock gap on high boost cars but you should get like the KB boost a spark or some kind of ignition setup like that to help the spark out a lil more.

I could be wrong but this is my understanding of it.

bhuff30 · Jul 28, 2008

04GTMustang is on track. Run the widest gap that your ignition system can support. You will know that you should decrease the gap if you get a mis-fire/spark blow out at full load. So run the stock gap. If it misses, then decrease the gap.
As for plugs, it won't hurt to run a colder plug. If the plug is too cold, you'll get a miss at idle because the plug will foul.

04GTMustang · Jul 29, 2008

bhuff30 said:
04GTMustang is on track. Run the widest gap that your ignition system can support. You will know that you should decrease the gap if you get a mis-fire/spark blow out at full load. So run the stock gap. If it misses, then decrease the gap.
As for plugs, it won't hurt to run a colder plug. If the plug is too cold, you'll get a miss at idle because the plug will foul.

sweet i was right lol. it happened to my brothers procharged 07 GT it started to miss right before redline put new plugs in and gapped to .035 and it went away.

twogts4us · Jul 29, 2008

darkside03gt said:
it depends on what whos supercharger you are running. vortech reccomends stock gaps and fresh plugs when you install the supercharger. but for guys who are really pushing it with more boost they need colder plugs. but i dont think adding them would hurt any aplication.

to the OP. you can decrease your gaps a little and it shouldnt hurt. i decreased mine by .006 or so with no issues. but that wont help you lean problem. do you have a wideband on your car? what the afr at ide? half throtle and WOT?

Why would you want to know what his AFR is at idle and partial throttle?

Yeah, with the COP ignition, the practice of closing the gaps is not as necessary. Some manufacturers still recommend it and many old school builders / modders will still do it, but the stock Mustang ignition is quite strong.

mogs01gt · Jul 30, 2008

bhuff30 said:
04GTMustang is on track. Run the widest gap that your ignition system can support. You will know that you should decrease the gap if you get a mis-fire/spark blow out at full load. So run the stock gap. If it misses, then decrease the gap.
As for plugs, it won't hurt to run a colder plug. If the plug is too cold, you'll get a miss at idle because the plug will foul.

Yep! The bigger the gap, the better the burn.

rw98gt · Aug 1, 2008

thanks guy's thats all i waunted to know. i was thinking the opposit the smaller he gap the better the burn.

blubullett · Aug 1, 2008

Bigger the gap the better the burn, till it blows out at 6 grand and it doesnt burn anything.

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