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Discussion Starter · #1 ·
These have 3 passes on them. Goldish color on end strap . Little lighter towards the base. dark till about the level of the plug threads on the insulator. I usually defer to the O2 sensor but I think its starting to get lead fouled . Anyone good at reading plugs? These are pretty cold -8 NGK's and this is the first time i have used this cold of a plug and I don't really know what to look for.

heres a pic...

 

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Here is a link I use. To me it looks like the timing might need to be retarded a little because of the location of the timing mark on the strap. The black tip and porceline might show a slight rich condition, although it could be from excess idle. Were these plugs pulled right after a run? How much nitrous are you running?

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


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<font size=-1>[ This Message was edited by: cahorne on 8/22/06 11:05pm ]</font>
 

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Discussion Starter · #3 ·
Unfortunately they werent pulled at the end of the run . Those were after I pulled the car onto the trailer after going into the pits. No nitrous on the three passes that were made on those plugs.
 

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I am not expert but the look lke they are running well. Maybe a little lean as they are almost white ashy looking. Best should be very light coat of ash with light brown color. I have removed plugs aftewr 12k and had them look as though just installed. it depnds on eitehr carb or injection. If black and dry merans oil in cylinders. Ifblack and dry means running very rich. Hope this helps. Paul in LA
 

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Discussion Starter · #6 ·
This whole plug reading thing has got me ordering up another O2 sensor to replace my lead fouled one . Then at least I'll get some meaningfull information. I dont know what tracks you guys go to but if I were to shut my car down at the end of the quarter mile and start yanking plugs out the track safety guys would have a coronary. Just pulling around to the pits is going to wipe of anything the plugs would tell me it seems.

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<font size=-1>[ This Message was edited by: mikeandnatasha on 9/4/06 9:10am ]</font>
 

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Can't you pull off on the return road and pull one? Usually there are turnouts on the return road for this and for guys who have chutes so they can bundle them up and not drag them the whole way back.
Look for the discoloration on the ground strap to be about 1/2 way between the end and where it's welded on the plug. Also, dont look at the porcelin for a temp or jetting guage...look at the flat area all the way around the base of the plug, where the ground strap attaches. It should be brown about 95% of the way. No less or it will be lean.
Then look at the porcelin and make sure you dont see any silver spots...this could be from detonation (actual piston melting to the porcelin).
And finally, there is a ditch in the middle of the porcelin, where the tip protrudes...look at the ditch before you run the plug...take a mental note of how it looks, then check it after you run the plug, and look for the ditch to stay the same. If it starts to fill in then there is too much heat either from the wrong plug or lean, or something causing leaness.
You agree Joe??
Brian
 

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Discussion Starter · #8 ·
Better to jet with a wide band air fuel meter or to use the plugs as an indicator ?
 
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