2 Spark Plug Questions (2 pics)…. - JeepForum.com

LinkBack Thread Tools
post #1 of 7 Old 10-10-2013, 05:39 AM Thread Starter
Web Wheeler
2Xtreme's Avatar
1979 CJ7 
Join Date: Dec 2003
Location: Schenectady
Posts: 1,446
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?

Name:  image-645178959.jpg
Views: 105
Size:  395.4 KB

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?

Name:  image-174844903.jpg
Views: 103
Size:  53.3 KB

2Xtreme is offline  
Sponsored Links
post #2 of 7 Old 10-10-2013, 11:59 AM
Registered User
Join Date: Mar 2008
Location: corpus christi
Posts: 7,057
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.

I don't feel like working on anything at this time so i sold my yj.
superj is offline  
post #3 of 7 Old 10-10-2013, 12:20 PM
Web Wheeler
Matt1981CJ7's Avatar
1981 CJ7 
Join Date: May 2011
Location: Elbert
Posts: 17,185

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.

Attached Thumbnails
Matt1981CJ7 is online now  
post #4 of 7 Old 10-10-2013, 12:24 PM
Registered User
1977 CJ5 
Join Date: Mar 2013
Location: Florence
Posts: 170
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!

1973 VW Karmann-Ghia first car
2009 Challenger R/T 6MT, Flowmaster, inTune daily driver
1977 CJ5 304, 3MT - under construction
And many in between!
MoneypitCJ5 is offline  
post #5 of 7 Old 10-10-2013, 12:47 PM Thread Starter
Web Wheeler
2Xtreme's Avatar
1979 CJ7 
Join Date: Dec 2003
Location: Schenectady
Posts: 1,446
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.....
2Xtreme is offline  
post #6 of 7 Old 10-10-2013, 12:56 PM
Registered User
1982 CJ7 
Join Date: Oct 2013
Posts: 44
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?
TheLaw360 is offline  
post #7 of 7 Old 10-10-2013, 04:47 PM
Web Wheeler
86cj74.2L's Avatar
2004 WJ 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 10,279
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.
86cj74.2L is offline  

Quick Reply

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome