I have thought for some time that the tune on my car is a bit fat, but before going through the trouble of starting to change out injectors and tune, wanted to get you read on the spark plugs. I took a picture of one plug. What do you think?

[IMG]http://i229.photobucket.com/albums/ee251/awheel73_photo/1996%20Yellow%20LT4%20383/IMG_1320a.jpg[/IMG]

[IMG]http://i229.photobucket.com/albums/ee251/awheel73_photo/1996%20Yellow%20LT4%20383/IMG_1319a.jpg[/IMG]

I know you don't use the NOS system much, but are you planning on removing it? How long have these plugs been ran I remember you mentioning they foul quick.

I have not used N2O for a long time. Without N2O and using street tires, it spins more than I would like, so N2O would be power than cannot be planted.

These plugs have about 2k miles on them. I usually change out much earlier, just wanted to get a better read on the plug. I'd like to keep it on the rich side, but it may be too rich, just wanting to see what ya'll think.

By the way, have you decided on your new motor platform? I'm about as excited as you about the build!!

A couple of things.

First you can't tell much about the important (burn you engine down) stuff from a plug once it's been driven around on the street. Or even idled for a few seconds. To properly read plugs you have to have a fresh set, one WOT pass, shut down right away and pulled to read.

On your plug you can see the base ring is completely black which just tells me that you idled the plug before you pulled. The porcelin below that is very important in spotting detonation. With it all black and fuel washed you can't see anything. A big mis-conception. In fact it dosen't tell you anything about the mixture.... All engines are rich at idle, espc one with any amount of overlap. Go pull a plug out a brand new Honda Civic ULVE after you let it idle for a few seconds and it will look the same.

I can however tell you some very general stuff.

I can also see all the gray/tan colored deposits on the upper part of the porcelin and electrode from unleaded fuel. The color tells me you basic tune up is a tad fat but it's not horrible for a street car. The light tan (almost white) we use for drag cars won't fly in a daily driver.

The ground strap has no color change on it untill it meets the body of the plug. That means the plug is too hot for your application. You want a decernable color change about 1/2 to 2/3 way down the ground strap. I'd drop you heat range to a NGK6... maybe go to a non-extended electrode type plug but the extended ones like you have work well in keeping a hot street motor clean when driven around in traffic all the time. They just don't work great with a lot of compression and long peroids of WOT. Definatly not for use with any NO2 you must uses a std electrode racing type plug. Its a trade off you have to make but if it were mine I would move to a TR6 and run it while and see if you need to move to a 7 to get the color change on the ground strap like it should be. Keep in mind you'll have to fool with the timing a bit to make it idle clean with a colder plug.

I see you have an index mark... I don't want to discourage you from trying to get the most from your stuff but.... it's a waste of time with flat top pistons. The only reason to spend time indexing plugs is so they wouldn't get closed up by the huge domes we use to run in 23 degree racing engines 25yrs ago.
Will

From what I've read, you can't accurately read plugs (at least for WOT and racing) unless you shut off the motor immediately after the pass. Just FYI, here are a few pages:

http://www.dragstuff.com/techarticles/reading-spark-plugs.html

http://www.dragstuff.com/techarticles/how-to-read-plugs.html

http://www.dansmc.com/spark_plugs/spark_plugs_catalog.html

http://www.4secondsflat.com/Spark_plug_reading.html

http://www.ngksparkplugs.com/tech_sup ... rk_plugs/faqs/faqread.asp

Matthew

Thanks for the great comments!

Matatk, I've read the NGK link, but thank you for the others. I've added them to my favorites folder. Great info!

Rklessdriver, also great info. I do not run N2O with these plugs, but do go with the TR6. Last time I tried this, I had to replace pretty quickly. I have not tried the TR7's. I'll need to give it a try. Also, are you sure it's a waste of time indexing? I don't obsess about getting them perfect; just try to make sure they are 75% pointed in the right direction.

Again, great info and keep it coming!

I'm positive it's a waste of time. Unless the piston dome is closing the gap up.... spend those extra 15 mins watching The View or something.

Now keep in mind, at my best I was just a fairly well recongnized regional engine builder with a good reputation for making horsepower. These days I'm just another former Marine who has a job doing stuff in variouse places for fun, adventure and of course the paycheck. I honestly haven't built more than 2-3 competition engines in the same year since 2002 when I closed up shop. Since then I've assisted a few people when I had the time and freshened up a few motors that I orginally build prior.... I know more than the average bear but I'm nobody in the big scheme of engine building.

However take a gander about 7 post down on this very topic. Joe Sherman is somebody and I'd take anything he says about engine building as the word of god. He will not lie to you. If he dosen't want to tell you something he will just tell you he isn't saying. He holds the same opinion I do about indexing plugs and has tested it far more times and far more recently than I have.

http://speedtalk.com/forum/viewtopic. ... ghlight=index+spark+plugs

I just proof read - and I realize that I may have come off a bit snippy... Sorry I don't mean it to. I'm about a 6 pack of New Castle and a T-Bone Steak into my Saturday night. At this point I can't figure a good non-confrontational way to say "I'm sure".
Will

No, I didn't take it as snippy, just like the information. Well, I won't worry about indexing them... I will try the 7's and see if that makes a difference. Worth a try, about $20 and an hour of time, so if it doesn't work, I'm not out much.