nuck

And who are n/a and not running E85. Who did or didn't change to a colder range of plug? What were your results?

Unreal

No plug change. 30hp gain, took 1-1.5 less timing. Milled 30 thousands

GunnerSMG

I went colder (tr7) .03* on the heads. I'm going to the dyno this Friday so I will let you know.

spra4u

Milled .050 and using a BR7EF plug from NGK. Z made 595hp on 93 pump.

383

Im doing .040 but the heads are not off yet. Im doing the tuning as well so Ill let you know.
Ive had problems with TR6's and longevity so I think Ill be using ZR1 plugs

rob20rx7

I'm pulling off my heads this week to replace my lifters. Should I mill them now that I have them out? Nothing crazy but I know I won't be able to go FI but just want to be close to 600 rwhp with my set up. Right now should be close to 580

vertC6

.040 will add 30+ hp and more importantly better drive ability

RedZ4me

milled .020 running ngk tr6's - no issues this whole summer at all

383

If you start getting "service charging system" codes try replacing the plugs first

rob20rx7

I can mill the heads to this .040 and still use 93 octane fuel no probs? what do you mean better drivability?

nuck

Mine are milled .030 with a ported intake, CNC and a Haltech. I am running fresh NGK TR6s which I believe are equivalent in range to the stock Delcos. I have the stock cam and exhaust so the only variable is the compression bump which should be less than a point. Lots of people with light mods seem fine with the stock range though.

Can there be a variation from car to car or should mine car be the same as every other car with .030 shave and the same gas?

Whis9

Why .040?

383

Sorry I missed this post.
I auto-x and wanted the torque and I have access to 100 octane. I think 12:1 will like the 100. I chose to run Denso IT22's I haven't been able to start it yet due to missing parts but anyone else running the IT22's?

Z0-SICK

My Z came with TR6's and after witnessing some rough idling I did a scan and came up with random misfires. I switched back to AC Delcos and problem gone. Only have a Halltech CAI though.

Vito.A

I'm going to try the new AC Delco ZR1 Iridium, 41-104 plugs. Found them on Amazon (JDM-Euro) for $4.98 each with free shipping. The LS1 forum folks are reporting good things on these plugs.

C6z06man

Haven't installed them yet but I'm milling .030 and putting in NGK TR6IX

lebvette

.030.....TR6....no problems.

Chonger

Mine were milled I believe .03 and I use NGKBR7 plugs. I went with a pretty cold plug.

edmundu

I originally had .020" milled, and ran NGK TR6IX & TR7IX. I was able to run more consistent timing with the colder plug. No fouling issues, plugs stayed clean.

I then had the heads ported & milled some more, total of .065". Car took like 3-4 degress less timing. I tried going to TR8IX, but they were definitely too cold, having part throttle stumbling/misfires.

I have settled on the NGK TR7IX, as they don't foul, and offer more consistent timing advance in warmer weather.

meatheadgn

Milled .030 with TR6. 91 octane at 4500 ft. elevation. UNREAL took the same basic timing out of mine as his I believe, about 1 to 1.5 degrees.