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-   -   What does this spark plug tell you experienced guys? (https://mustangforums.com/forum/5-0l-1979-1995-mustang/631605-what-does-this-spark-plug-tell-you-experienced-guys.html)

Quickbird144 02-07-2011 06:42 PM

What does this spark plug tell you experienced guys?
 
Stock 302, efi, cai, flowmaster catback exhaust. That's it.
This is what all of my spark plugs look like, is this a good sign?

http://i83.photobucket.com/albums/j2...IMAG0044-1.jpg

1987gt40ttop 02-07-2011 07:13 PM

i cant tell from the picture but it looks like its a little redish, which would indicate heat or a sign that maybe your car is running a little lean or possibly the plugs were gapped wrong when they were put in , other than that theres no signs of detonation or any build up from oil or carbon

83fox50 02-07-2011 07:13 PM

that spark plug looks brand new. which means its not running too rich or too lean. how many miles are on those plugs?

Quickbird144 02-07-2011 07:20 PM

Thanks for the swift reply guys.

1987, the pic may have came out that way but these plugs were as white as day. Which worried me a bit since I bought brand new ones to replace them :/ They were all gapped at .54 as well.

83fox, they looked the same to me. But looking around, the inside of the plug, not the insulator, being all black like it is says that I'm running lean. So I have no idea. Before I got the car, cannot say how many miles. But I've put about 500-600 on them since I've had it.

83fox50 02-07-2011 07:35 PM

ordinarily you wont be able to see the bottom of the insulator, just the tip is really visible and it should be a light gray or brown.
i bet those were changed right before you bought the car.
use this for reference:
http://www.mudinmyblood.net/forum/im...park_plugs.jpg

Quickbird144 02-07-2011 07:38 PM

Yeah I went by that many times but didn't see mine on there. Lol. The car had a complete tune-up before I got it. Everything looks new down to the oil. The PO definitely took extreme care of it, there's no question about it. I'm just a bit curious. I'll pull them out tomorrow and see what they look like now. That picture was taken around 100 miles, after I got it that is.

Venomantidote95 02-07-2011 08:04 PM

Durrrrrr! Fresh tune up? Unless u have a problem it takes quite a few miles to change the plugs enough to makem look anything other than new!

67mustang302 02-07-2011 09:51 PM

The reddish tinge is normal due to additives in modern fuels.

The flat metal surface facing the chamber at the ends of the plugs looks clean, so idle fuel is good. The coloration is burned off on the first 2 turns of the threads, indicating heat range of the plug is about where it should be. Electrode and ground strap are clean, indicating good ignition.

You'd need a brand new plug run at WOT and then shut down and pulled to see ignition timing on the ground strap. And if you also cut the metal body off where the threads are or use a doctors ear/nose/throat scope to look at the base of the white insulator where it meets the plug body, you can see WOT fuel.

For timing you want a bluish metal discoloration right about the apex of the ground strap, half way between the tip and plug body. Fuel, a greyish ring(known as the fuel ring) at the base of the insulator going about 3/4 of the way around is indicating lean best power but may be costing some peak torque. A fuel ring all the way around is considered a safe best power with solid peak torque. The thicker the ring, the more the fuel, a non existent ring or less than 3/4-1 full turn around the base indicates too lean.


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