Spark plugs full of soot!!! - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Hotrodding Basics
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 11-19-2008, 03:25 PM
muzzfactor's Avatar
Registered User
 
Last photo:
Join Date: Sep 2005
Location: San Antonio, TX
Age: 44
Posts: 99
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Spark plugs full of soot!!!

Hey guys, all my spark plugs are fouled out on my truck (84 GMC). They are completely black with soot. What does this mean? Thanks.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 11-19-2008, 03:44 PM
carsavvycook's Avatar
My 2 cents worth
 
Last photo:
Join Date: Sep 2007
Location: Lakeside, CA
Age: 57
Posts: 2,855
Wiki Edits: 3

Thanks: 2
Thanked 2 Times in 2 Posts
Running too rich.

Possibilities also include, weak spark, low compression, spark timing too retarded, wrong spark plug, plug gap, wrong plug heat range.

What engine, what heads are on it, and how many miles were they run?
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 11-19-2008, 06:45 PM
muzzfactor's Avatar
Registered User
 
Last photo:
Join Date: Sep 2005
Location: San Antonio, TX
Age: 44
Posts: 99
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
It's a late 70's modlel 350. I did a compression test and all cylinders are at least 160. Not sure about the heads, but have never had a problem with it since it was rebuilt 30,000 miles ago. The plugs didn't even have 100 miles on them. They were the AC R44t, but i switched today to the r45ts gapped at 45. I've got an Edelbrock 1405 carbureator on it also.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 11-19-2008, 07:09 PM
carsavvycook's Avatar
My 2 cents worth
 
Last photo:
Join Date: Sep 2007
Location: Lakeside, CA
Age: 57
Posts: 2,855
Wiki Edits: 3

Thanks: 2
Thanked 2 Times in 2 Posts
Is it a HEI, or points distributor? During the previous tune-up, did you have to adjust the timing?

Either way, look at the harmonic balancer. The rubber between the hub, and the outer half could be cracked enough to allow it to spin a little bit. This will move the 'mark' on the balancer away from the 'zero' mark on the timing tab.The only way to check this is to bring #1 piston to TDC compression.

I'll bet that 1405 Edlebrock Carb, needs a couple of adjustments.

What port did you hook up the distributor vacuum to? Manifold, or Ported?
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 11-19-2008, 07:12 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 13,083
Wiki Edits: 326

Thanks: 779
Thanked 1,057 Times in 879 Posts
Have you changed fuel pumps? If so, did you re-check the pressure at the carb? 5 psi is all you need.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 11-19-2008, 07:14 PM
Registered User
 
Join Date: Dec 2004
Location: San Jose Ca
Age: 62
Posts: 472
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
1405

1405 carbs have no tubes for manifold vacuum,which may be part of the problem,what is your timing set?You can adapt a manifold vacuum source from the pcv port.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 11-19-2008, 07:42 PM
carsavvycook's Avatar
My 2 cents worth
 
Last photo:
Join Date: Sep 2007
Location: Lakeside, CA
Age: 57
Posts: 2,855
Wiki Edits: 3

Thanks: 2
Thanked 2 Times in 2 Posts
Quote:
Originally Posted by SDLuck
1405 carbs have no tubes for manifold vacuum,which may be part of the problem,what is your timing set?You can adapt a manifold vacuum source from the pcv port.
Thanks for reminding me I forgot about the 1405 not having that port. Most of the Edlebrock carbs I have worked on lately are 1406's.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 11-19-2008, 08:55 PM
muzzfactor's Avatar
Registered User
 
Last photo:
Join Date: Sep 2005
Location: San Antonio, TX
Age: 44
Posts: 99
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I have an HEI and the vacuum advance is currently running off of the carb, which after reading many posts I believe that I should be running it off the manifold......correct? What vacuum lines should be running to the carb? Tomorrow I'm going to plug the two on front of the carb and just use the pcv in the middle of the carb. This carb was just rebuilt last week and seemed to be running better before I took it in. I will definitely take a look at the harmonic balancer also.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 11-19-2008, 09:12 PM
carsavvycook's Avatar
My 2 cents worth
 
Last photo:
Join Date: Sep 2007
Location: Lakeside, CA
Age: 57
Posts: 2,855
Wiki Edits: 3

Thanks: 2
Thanked 2 Times in 2 Posts
Just make sure you have manifold vacuum to the distributor, and if you have a vacuum gauge, post your manifold vacuum reading at hot idle.

This will help us identify your problem.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 11-21-2008, 11:59 AM
runn141's Avatar
SB S10
 
Last photo:
Join Date: Sep 2006
Location:
Posts: 1,258
Wiki Edits: 0

Thanks: 21
Thanked 15 Times in 15 Posts
on a 1405 edelbrock the vacuum port on the right hand side facing the carb is the full port vacuum, same as the intake. the stock fuel pump will have pressure from 7 to 9 psi. ive already experienced this with the same carb and had to install a regulator.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 11-21-2008, 01:32 PM
Henry Highrise's Avatar
Lost in the 60's
 
Last wiki edit: Removing stuck fasteners Last photo:
Join Date: Dec 2001
Location: Dixieland
Age: 69
Posts: 15,189
Wiki Edits: 4

Thanks: 0
Thanked 11 Times in 10 Posts
Sounds to me like you are gasing your plugs....carb float set too high? Choke not opening all the way? Carb air/fuel mixture not set right? Fuel pressure too high and over riding needle and seat? You have something giving you a rich condition....thus the black sooty looking plugs.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 11-21-2008, 06:37 PM
Registered User
 
Join Date: Dec 2004
Location: San Jose Ca
Age: 62
Posts: 472
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
1405 made at this time, do not have a manifold vacuum port, only ported and pcv.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 11-21-2008, 07:22 PM
Registered User
 
Join Date: Dec 2004
Location: San Jose Ca
Age: 62
Posts: 472
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Ck vacuum ports with a vacuum guage,ck vacuum advance to see if timing is changing,What is timing set at and what is total? Is the intake manifold sucking oil from the bottom of intake,what is engine vacuum at idle? Give us some more information?
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 11-24-2008, 04:57 AM
muzzfactor's Avatar
Registered User
 
Last photo:
Join Date: Sep 2005
Location: San Antonio, TX
Age: 44
Posts: 99
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Fixed!!!

Hey guys, I took the carb to a carburetor shop and they made sure everything was okay then I made sure and used the vacuum straight off the manifold and now it's running GREAT!!! I didn't have anyway the check how much vacuum i'm using but she's never ran better. Thanks for all your help guys.
Reply With Quote Quick reply to this message

Recent Hotrodding Basics posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

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

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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
motor wont start spark plugs have oil on them 54chevy22 Engine 3 09-11-2006 06:59 AM
motor wont start spark plugs have oil on them 54chevy22 Engine 13 08-10-2006 09:28 AM
Spark Plugs 65Stanger Engine 3 05-10-2006 09:52 PM
Dart iron eagle spark plugs... killerformula Hotrodders' Lounge 10 09-18-2004 11:33 AM
spark plugs abe Engine 1 12-19-2002 03:47 PM


All times are GMT -6. The time now is 07:43 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.