What does this spark plug tell you experienced guys? - MustangForums.com


5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

Reply
 
 
 
Thread Tools Search this Thread
Old 02-07-2011, 06:42 PM   #1  
Quickbird144
1st Gear Member
Thread Starter
 
Join Date: Jan 2011
Location: Orlando
Posts: 109
Default 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?

Quickbird144 is offline   Reply With Quote
Old 02-07-2011, 07:13 PM   #2  
1987gt40ttop
1st Gear Member
 
Join Date: Jan 2011
Location: NJ
Posts: 84
Default

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
1987gt40ttop is offline   Reply With Quote
Old 02-07-2011, 07:13 PM   #3  
83fox50
1st Gear Member
 
83fox50's Avatar
 
Join Date: May 2008
Location: Indiana
Posts: 87
Default

that spark plug looks brand new. which means its not running too rich or too lean. how many miles are on those plugs?
83fox50 is offline   Reply With Quote
Old 02-07-2011, 07:20 PM   #4  
Quickbird144
1st Gear Member
Thread Starter
 
Join Date: Jan 2011
Location: Orlando
Posts: 109
Default

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.
Quickbird144 is offline   Reply With Quote
Old 02-07-2011, 07:35 PM   #5  
83fox50
1st Gear Member
 
83fox50's Avatar
 
Join Date: May 2008
Location: Indiana
Posts: 87
Default

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:
83fox50 is offline   Reply With Quote
Old 02-07-2011, 07:38 PM   #6  
Quickbird144
1st Gear Member
Thread Starter
 
Join Date: Jan 2011
Location: Orlando
Posts: 109
Default

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.
Quickbird144 is offline   Reply With Quote
Old 02-07-2011, 08:04 PM   #7  
Venomantidote95
4th Gear Member
 
Venomantidote95's Avatar
 
Join Date: Jul 2008
Location: alabama
Posts: 1,812
Default

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!
Venomantidote95 is offline   Reply With Quote
Old 02-07-2011, 09:51 PM   #8  
67mustang302
6th Gear Member
 
Join Date: Apr 2007
Location: California
Posts: 10,468
Default

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.
67mustang302 is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
2002 Mustang GT Premium 5 Speed JonnyBlazeGT Mustangs For Sale 3 11-03-2015 01:10 AM
New guy here from SE Michigan movielover40 New Member Area 5 08-27-2015 10:13 PM
White smoke gone, now grey smoke. overnight89 4.6L General Discussion 6 08-22-2015 09:02 PM
crank position sensor 2004 mustang 3.9 v6 microgt V6 (1994-2004) Mustangs 2 08-20-2015 07:12 AM


Tags
1987, 50, build, ford, good, lean, modified, mustang, obsessive, plug, plugs, rich, running, spark, whats, wrong

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not 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 Off
Refbacks are Off

Forum Jump

Advertising
Featured Sponsors
Vendor Directory

All times are GMT -5. The time now is 05:00 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.