Well, these plugs have about 2K miles on them since the rebuilt TII motor was installed. I'm running 12-13 psi with a walbro, GReddy FMIC, Rtek7 1.5 ECU, stock injectors and no emissions. EGT's peak @ 700 on my GReddy gauge through a WOT run in third gear.

I think they look damn good if not a tad on the rich side. I replaced these with a set of 9's all around (these were stock plugs, 7 leading, 9 trailing). They didn't need replacing at all but I thought I'd try all 9's out.

Thoughts?

 

looks very rich on the rear rotor, and a little clogged and worn for 2K miles... but otherwise they look fine.

I would have guessed 5-8k miles on the leadings by the way they look.

 

Reminds me mark, you get set up to deal NGK plugs yet?

 

It looks like these plugs were in during the easy driving break in period where they accumulated more than normal deposits.

Then when you started to run up the power the deposits started to burn off.

I suspect your tune is pretty good.
To get a good plug read, clean them & run them again, then recheck them.

PS: When I tried 7's in the trailing position, they fouled.

 

I have leadings in the regular NGK available right now

 

They're on your site? K, I'll check later today

 

I'm running all 9's now, I'll pull them in another 1K and see how they look. After the first day or two of running/idling once the rebuild was first started/installed, the set of plugs pictured were installed and I started driving the car for break in. I changed the oil @ 500 miles, added some boost around 800 miles and full boost/revs around 1100 miles since the motor felt strong and started consistently. This motor never had any flooding issues throughout the entire break in. I had 2 floods last week, both on hot starts on muggy humid rainy days. I found a vacuum leak in the TID and changed my very old spark plug wires and it's been 100% again ever since, hot starts and all. So, these plugs were in the car since the motor had like 5 miles on it I'm pretty happy with the way they look as well as the motor/swap in general. BTW, this is one of Kevins rebuilds/streetports from rotaryresurrection.

 

Should be about half way down this page:
http://www.mazdamark.com/prod01.htm

 

Why would you put hotter plugs in the trailing?

 

do the numbers derive from the part number of the plug? ex. 7 = BUR7EQ

and whats the advantages of running all plugs with 9? or 7?

 

Yes that's where the #'s 7 and 9 come from.

On turbo motors you might want to run a cooler plug (9's in this case) if it's been modded a little (like jon88se is doing).

As far as the stock motors 7L and 9T that's probably the best setup.

 

Yeah, I agree, if you have a moderately modded car, you should run all 9s.. The 7s are just in there for emissions purposes..