one lean cylinder. - Ford Muscle Forums : Ford Muscle Cars Tech Forum
 
LinkBack Thread Tools
post #1 of 6 (permalink) Old 07-27-2002, 05:04 PM Thread Starter
Registered User
 
Join Date: Jul 2002
Posts: 4
one lean cylinder.


On my 289 cyl. number 6 always had shown a hotter/lean spark plug condition. It's close to white while all the other are pale brownish. Particuliar to that same spark pliug is the threads are oily. I ran a compression test and all cyl. were steady at around 130-135. Its a performer intake and I plugged the vacuum gauge onto one of the vacuum port wich was common to the runner feeding cyli. 6 and at 2000 rpm the needle stayed steady at around 25 inches. What else than a leak could cause that situation?
I put 3000 miles on that recent rebuild and that's been like this since day one...the engine runs good,no oil consumation,easy starting,good idle altough lumpy because of the cam.
What else should I check?

thanks.
cobra289 is offline  
Sponsored Links
Advertisement
 
post #2 of 6 (permalink) Old 07-27-2002, 06:22 PM
Registered User
 
Join Date: Mar 2001
Location: Vancouver Island
Posts: 231
one lean cylinder.

I would suspect that you have a small vacuum leak on the bottom side of your intake manifold runner that corresponds to the lean cylinder. Since the leak would be pulling in air and oil mist from the cam valley that would also explain why there was also oil on the #6 plug that weren't on the others.
Mach1Morgan is offline  
post #3 of 6 (permalink) Old 07-27-2002, 07:36 PM Thread Starter
Registered User
 
Join Date: Jul 2002
Posts: 4
one lean cylinder.



Thanks mach1....Would retorquing the intake bolts be the way to cure that leak? It's a performer and that reminds me the aluminium parts need to be retorqued once in a while don't they? does 30-35 pounds sound like right as a good torquing ?

Just a note concerning my initial message is the oil deposit is only on the threads of the spark..the tip and insulator are close to white with no oil.

thanks again.
cobra289 is offline  
 
post #4 of 6 (permalink) Old 07-27-2002, 08:52 PM
Registered User
 
Join Date: Mar 2001
Location: Vancouver Island
Posts: 231
one lean cylinder.

My book says to torque the intake manifold bolts to 25 ft/lbs.
Mach1Morgan is offline  
post #5 of 6 (permalink) Old 07-29-2002, 07:51 PM Thread Starter
Registered User
 
Join Date: Jul 2002
Posts: 4
one lean cylinder.


I've checked for leaks without success and torqing to 25 was all good....now has anyone ever heard about faulty intakes that by configuration could be responsible for a bad fuel/air mixture and thereby be the source? It's been suggested to me by a person who had as much as three temperature range showing on the sparks: too rich,just right and lean.....that was on one of the high-rise "cobra" repro.Anyone ever experienced similar problem?
cobra289 is offline  
post #6 of 6 (permalink) Old 07-30-2002, 01:42 AM
RPM
Registered User
 
Join Date: Jan 2001
Location: Bakersfield, Ca
Posts: 698
one lean cylinder.

This is an area where Smokey Yunick though there was much to learn. His belief was if you could equalize cylinder temps by varying timing, comp ratio, cooling, for each hole, you would increase the point at which detonation would occur. He said the #5 cyl on SBF would get the hottest due to inefficient water cooling. Interesting.
RPM is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Ford Muscle Forums : Ford Muscle Cars Tech Forum forums, you must first register.
Please enter your desired user 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:
OR

Log-in











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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

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