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Unread 10-10-2013, 05:39 AM   #1
2Xtreme
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2 Spark Plug Questions (2 pics).....

Pulled my plugs to do a compression test and found this stripe down the side of the insulator on the #2 plug.
Anyone know what causes this?

image-645178959.jpg

Also, on the 258 using the standard Autolite 958 plugs, are the gaskets generally used?
And if so, which way do they go (large O.D. up/ down)?
Or does it matter?

image-174844903.jpg

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Unread 10-10-2013, 11:59 AM   #2
superj
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i would put those gaskets so the flat edge sits against your plug, like in the picture you put up.

as far as the stripe, thats crazy.
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Unread 10-10-2013, 12:20 PM   #3
Matt1981CJ7
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2X,

I think the staining just indicates how your plug was indexed in the cylinder. That's the combustion side and it's normal for it be a little darker. That one appears awfully dark (rich), though. Are the rest a similar color?

Here are mine after about 2500 miles on my rebuilt 360. As you can see, they are starting to get a similar burn pattern on the insulator tip, just not as dark as yours.

Matt
sparkplug3456.jpg  
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Unread 10-10-2013, 12:24 PM   #4
MoneypitCJ5
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That almost looks like its arcing to the threaded base instead of the electrode. Weird...

I just did a tune-up on my Challenger and discovered NGK plugs tend to turn the ceramic red. So I guess weird stuff happens!
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Unread 10-10-2013, 12:47 PM   #5
2Xtreme
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Quote:
Originally Posted by Matt1981CJ7 View Post
...That one appears awfully dark (rich), though. Are the rest a similar color?
They are.
Thing is there are ZERO miles on the plug.

I am trying to get a replacement engine running well enough to determine if it, or my original, she be the one rebuilt.

Thing seems to be running on 3 cylinders.
Has spark to all cylinders and good compression.
Pulled wires 4, 5 and 6 one at a time - neither made a difference. Pull any of the other 3 and it dies.

But that's a different thread.....
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Unread 10-10-2013, 12:56 PM   #6
TheLaw360
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I'm going to agree with arcing to the threads. spend 4 bucks and get a new one see if it does the same thing?
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Unread 10-10-2013, 04:47 PM   #7
86cj74.2L
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Once again Matt beautiful plugs.

One side will show color.

Back in 06 or something JH had a little blurb about why on the 258 the one side of the plug is clean and the other side shows color.

It looks too dark. But you won't know the truth till all cylinders are working and under load.
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