Blown 4-banger

Just eye ball it! You should be able to tell the difference between .037" and .040"

Matty

Feels like it sometimes when the parts come to the door.

Matty

Oh ya for anyone wondering...the BKR7EIX's were out of the box at 0.028"

OniMirage

so I changed em and normally you wouldnt feel much of a difference but in my case yes ... yes you do feel a big difference. Why you ask? well after taking out the old clearly defeated plugs it is clear to see that they could not hold up to the temps put out with the added boost of stage 2 for over 3k miles after being stock for over 10k miles. All the new plugs were slightly off so I regapped em to .40 each. Now your probably wondering so the old plugs were damaged simply to do with use right and they should only look slightly chared. Well you would be right until you checked the gap on the old plugs and saw the build up on them. The gaps were COMPLETELY random. Over time plug gap should increase due to stress but in my case THEY COMPRESSED. Yes you read that right no need to adjust your monitor. As I took out each old one and put in the new ones a buddy checked each plug. He says "this one is .28 just like I use" "about .25 here" ... .31 and .34. My car had only minor issues every so often when starting but the big issue was power and looks like I got it back ... all of it. Acceleration has no hesitation at any point in the range and the car now responds much quicker. I went to a road that is basically a back road with no traffic at all since it is a dead end. I started in 2nd rolled and accellerated to the top of 2nd let off turned and drove like normal accellerating in 2nd from 2k to the top and let off. Again driving like normal I accellerated in 2nd from 4k to top end no hesitation. Couldn't really do it in 3rd cus the road isn't really all that long. But tried a couple times while on the way home and no hesitation to report except for the good side affect of RESPONSE.

So for my report I would say if you go to a 3.0 pulley you will want one step colder plugs to get the most out of the added power.

cmj917

I just installed by NGK BKR7E's last night and drove the car into work this morning. It seemed like the throttle response was a bit better, but my concern is that I'm getting brief knocking between gears (on the Interceptor). Maybe I just never paid attention before, but it looks like anything between .5 and 1.5 degrees of knock right after the 2-3 and 3-4 shift (right when I take my foot up off the clutch), and the car feels like it lags for just a split second.

Anyone else experiece this or have any advice on whether or not this is normal?

OniMirage

dont have that meter to see it but as I hear those lil devices aren't doing a very good job lately ... as a side note did you make sure the gap was correct?

cmj917

I have one of the older Interceptors (b/f the ones w/ the shift light, etc.) and have never had a problem with it. As far as the gap is concerned, they're all .037. Should I consider going to .040?

Thanks.

OniMirage

I didnt try .37 but the recommended gap is .40 no matter what type you use. I would say re gap and see what happens. The only thing you would lose is about 20 minutes of time.

Asphalt Assault

just a word of caution. if plugs come pregapped it does not mean just put them in. it is done this way so a technician can save time. they always check them to be sure any way. If you were to just put the plugs in then that would be like giving a patient medication without checking the dose is correct.

OniMirage

they were all slightly off one was way off so checking was the way to go ... I just didn't have the tools to check at the time which is why I was freakin out

OBSSSD

Copper plugs are the best for performance and I don't think you can argue that based upon experience. The iridum and platinum plugs are simply going to detonate easier so why bother with them for more money? The copper plus are easy to replace on the Cobalt and last 50,000 miles plus they are cheap! I got my BKR7E's at O'Reiley's here in Dallas for like $1.59 each. The stock gap is usually .032" to .040" from what I have seen so why would you want to gap larger than that at .045"? It may work ok but the stock gap is listed at .040" for a reason. I'd say use .040" for anything above 2.8" and .035" for anything 2.8" or below.

All IMO

OneFast20

well this is probably the hardest mod yet haha...after reading what everyone had said i decided to with .40 for my stage 2...and it made a huge difference. Its runs really smooth...so thanks to CTCOBALTSSS for the defenite answer on that one

Matty

My story.

Got stage 2 and the 2.8". Had them installed along with the BKR7E's gapped at .037". A hestitation insued which I thought was a mis-fire but turned out the stage 2 flash along with the AEM intake was causing a lean condition at certain throttle positions.

Tried the BKR7IEX's gapped at .040. Had them in for about a month. Seemed no different in performance or driving etc. I guess with the heat and/ or me not noticing, I was getting detonation. I just recently started to hear the detonation rattle for a split second, coming from underneath.

So yesterday I put the BRK7E's gapped at .037" back in. Was a relatively hot day and I got onto the throttle about a half dozen times. The rattle did not come back.

So the few guys that have said all along that the iridium plugs cause detonation appear to be right.

Stick with the copper BRK7E's between .035"- .040". JMHO.

Ljavy17

My one step colder plugs are perfect with my 2.6 gapped at 35. ( 0 knock, and even tho it has nothing to do with it AF of 11.5 to 12.0)