[Gandalf]

^If it ain't broke, don't fix it! lol
If you do change them, check the gap on the old ones, just for curiosity.

 

[Gandalf]

UPDATE:
I think I was previously just at the threshold for power without miss using my MSD setup, .033 gap, and the stock ecu, producing 300whp @ 17 psi.

The coppers I just installed at their stock gap of .033 or so, they also developed the same miss, even worse actually, as of yesterday. I am pushing a bit more boost now though, topping out at about 19 psi (94 octane, J&S knockguard and tuning help me against knock)

Because I am tuning with a new setup (EMS, 1050cc injectors etc) the power increase now demands a smaller gap. Regapped them @ .028, and it worked.

I threw the Iridiums back in regapped to .028, but they missed still. It was just their time.

So there's some data regarding gap + MSD.

I added edits to my above posts, otherwise they can be misleading.

 

[Gandalf]

I haven't touched gap on any Iridiums yet, they look a bit delicate to pressure the tips, avoid putting pressure there if you try to gap them. I'm going to experiment on copper gaps.

 

[Gandalf]

^Excellent.
I think the MSD + racing/tuning just takes its toll... And I'm 100% certain it was the plugs, it was the only thing changed; and the miss issue was resolved within 10 minutes, so all other conditions remained the same, and stayed that way since.

Tempting to do a comparison of the two plugs, and gaps (maybe bigger like .038) next time on dyno, I like to read the plugs whenever I get moderate knock on the J&S, to see if one cyl is worse than others.

Edit - UPDATE:
I think I was previously just at the threshold for power without miss using my MSD setup, at .033 gap, and the stock ecu, producing 300whp @ 17 psi.
Because I am tuning with a new setup, the power increase now demands a smaller gap. I threw in coppers at their stock gap of .033 or so, they also developed the same miss, even worse actually, within a couple of days. Regapped them @ .028, and it worked.
I threw the Iridiums back in regapped to .028, and they still missed... it was their time.

 

[Gandalf]

Wait.

They look perfect, but they began to miss?

So are they OK or did you only get 10k km out of them?

Exactly. There was no visually identifiable reason (gap, coloration, build-up, good tips, etc)... they were installed in 2012, got 10,000+ km out of them (I don't put dd miles on the car), and the gap was identical to when installed. That's pretty good in my books. How much mileage do you typically see from your plugs?
I have the MSD 6A ignition, so they probably see a more challenging environment with multiple sparks at low RPM.

Considering I always had to fiddle with the coppers (widening gap after only 2000km), I'm temporarily trying coppers now and leaving them stock gap (.033), until I pick up some more Iridiums.

Jim, I would swap out the plugs first, if your miss is still there, throw the older ones back in, no harm done and you can still use the new plugs when the time comes. I haven't had issues with the crush-washers leaking on re-use AFAIK. My miss drove me nuts this past week because I was working on timing/boost and I didn't know what was holding me up, lol. What do you know, Iridiums aren't invincible

Edit - UPDATE:
New-found power is demanding a smaller gap.

 

[Gandalf]

Update: absolutely no change after 10,000 km on the Iridiums. They look perfect. They began to miss last week.

Edit -
2nd UPDATE:
I think I was previously just at the threshold for power without miss using my MSD setup, with .033 gap, and the stock ecu, producing 300whp @ 17 psi.
Because I am tuning with a new setup, the power increase now demands a smaller gap. I threw in coppers at their stock gap of .033 or so, they also developed the same miss, even worse actually, within a couple of days. Regapped them @ .028, and it worked.


Edit -
3rd UPDATE:I threw the Iridiums back in regapped to .028, and they still missed.

 

[Gandalf]

^That's what I was going on, if it ain't broke don't gap it lol

I am curious to see if the gap changes over time on these though.

 

[Gandalf]

on the ngk iridium, what gap do you guys gap it at, stock or .028?

I checked them (bkr7eix) and they were all the same out of the box, and they were all at .030 or .032 (can't quite remember), so I left them as is to see how they would do. No issues. But like I said I am only at 300whp and 17 psi with MSD 6a, stock ecu.

Here is an earlier thread of mine regarding "growing gaps" on my BKR7E's. Not uncommon for them to increase .006

I agree that it comes down to how often things are getting taken apart anyway, and how often people want to be changing/gapping plugs.

 

[Gandalf]

I am running iridiums, with MSD 6a, I found my coppers were increasing gap quickly to like .034+, so I thought I'd try the iridiums, and recently dyno'd 300whp@17psi still on stock ecu (gen2) with about 7000km on the plugs... and no hesitation. So I think I might be converted just for the consistency and longevity.