SUPPORT OUR SPONSOR

Go Back   Club Cobra > Club Cobra Tech Areas > Shop Talk

Welcome to Club Cobra!  The World's largest non biased Shelby Cobra related site!

  •  » Representation from nearly all Cobra/Daytona/GT40 manufacturers
  •  » Help from all over the world for your questions
  •  » Build logs for you and all members
  •  » Blogs
  •  » Image Gallery
  •  » Many thousands of members and nearly 1 million posts! 

YES! I want to register an account for free right now!  p.s.: For registered members this ad will NOT show

Keith Craft Racing
MMG Superformance
Main Menu
Nevada Classics
MMG Superformance
MMG Superformance
Advertise at CC
Banner Ad Rates
MMG Superformance
MMG Superformance
MMG Superformance
Keith Craft Racing
March 2017
S M T W T F S
      1 2 3 4
5 6 7 8 9 10 11
12 13 14 15 16 17 18
19 20 21 22 23 24 25
26 27 28 29 30 31  

Kirkham Motorsports

Like Tree2Likes
  • 1 Post By Tommy
  • 1 Post By Phx Mike

Reply
 
LinkBack Thread Tools Display Modes
  #1 (permalink)  
Old 03-13-2017, 11:28 AM
Registered User
Visit my Photo Gallery

 
Join Date: Aug 2012
Cobra Make, Engine:
Posts: 3
Not Ranked     
Default Alternator Rating Question

I own a 427 cobra which has developed a problem in the electrical system which I think may be related to the alternator not producing the required output. I cannot find any markings on the housing to indicate the min and max amperage ratings and hoping that someone could provide that info. The car has two push fans on the front side of the radiator and one large pull fan mounted on the inside , two electrical fuel pumps and a MSD pro billet distributer, coil and 6AL. Thanks
Reply With Quote
Sponsored Links
Sponsored Links
  #2 (permalink)  
Old 03-13-2017, 12:44 PM
CC Member
Visit my Photo Gallery

 
Join Date: Apr 2008
Location: Near Chichester, Sussex by the sea......, UK
Cobra Make, Engine: Crendon 427 S/C 428 FE+toploader
Posts: 608
Not Ranked     
Default

maybe useful to state what the problems are. Is it the charge light failing to extinguish?
__________________
Crendon 427, in the making
http://crendonreplicas.com/
Reply With Quote
  #3 (permalink)  
Old 03-13-2017, 08:22 PM
Dwight's Avatar
Senior Club Cobra Member
Visit my Photo Gallery

 
Join Date: May 2001
Location: Florence, AL
Cobra Make, Engine: Lone Star "sold" and RCR GT 40
Posts: 4,069
Not Ranked     
Smile

To check the output of the alternator use a volt meter.

Check the voltage before you start the motor at the battery. Should read about 12 -12.5 v.
Then start the motor and check the voltage at the battery. It should read more. 13-14 volts.
__________________
''Life's tough.....it's even tougher if you're stupid.'' ~ John Wayne
"Happiness Is A Belt-Fed Weapon"
life's goal should be; "to be smarter than inanimate objects"
Reply With Quote
  #4 (permalink)  
Old 03-14-2017, 04:38 AM
Tommy's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2002
Location: Dadeville, AL
Cobra Make, Engine: E-M 427 light weight body, 410 Windsor
Posts: 1,949
Not Ranked     
Default

Doug,
I have two suggestions. First is to look for any identifying part numbers that you could use to research the capacity of your alternator. They would be the same numbers you would use if you wanted to go to the parts store to replace it.

Second, think of the battery as a reservoir of electrical power that fills in for the alternator when it is not making enough power (e.g., when starting the engine), and takes back power from the alternator to refill the reservoir when the alternator is making more power than the other electrical systems need. That means an underproducing alternator would leave the battery power lower after running the engine than before. As Dwight said, you can read that effect with a voltmeter. ... Here's what I would do. First, fully charge the battery with a charger. Let is sit for a while to reach its steady state and then check the voltage (e.g., 12.4 volts). Then start the car, let it warm up a bit and then check the voltage at the battery with only essential electrical systems on. Check it at idle and at about 2,000 RPM. It should be above 13 volts. Now drive the car for 30 minutes or more without stopping or restarting the engine. When you do stop, turn off everything and check the battery voltage again. If it is less than the the voltage of the fully charged battery (e.g., 12.4), then the electrical system is not sufficiently replenishing the power reservoir in your battery. This could be due to a bad battery, failing alternator, undersized alternator, or bad voltage regulator. If I had these symptoms I'd first have the battery checked and, if it passed, I'd have the alternator output checked. Most chain parts stores can do this.
Doug R likes this.
__________________
Tommy
E-M 66 427SC, Ford 410 Windsor, Richmond 5 speed, Corvette suspension.
"Never attribute to malice that which is adequately explained by stupidity." - Hanlon's Razor
Reply With Quote
  #5 (permalink)  
Old 03-18-2017, 01:42 PM
Registered User
Visit my Photo Gallery

 
Join Date: Aug 2012
Cobra Make, Engine:
Posts: 3
Not Ranked     
Default

Thanks the comments were very helpful and the testing as described show the voltage under load at about 1800 rpm was less that the basic battery voltage of 12.65v engine not running. At idle no load was 12.95V, Idle under load at 12.35v and at 1800 rpm the voltage was 12.52v . So I guess the alternator is suspect.
Reply With Quote
  #6 (permalink)  
Old 03-18-2017, 05:46 PM
Phx Mike's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Apr 2016
Location: Phoenix, AZ
Cobra Make, Engine: Kirkham 427 s/c with Pond block 482 FE
Posts: 302
Not Ranked     
Default

Quote:
Originally Posted by Doug R View Post
Thanks the comments were very helpful and the testing as described show the voltage under load at about 1800 rpm was less that the basic battery voltage of 12.65v engine not running. At idle no load was 12.95V, Idle under load at 12.35v and at 1800 rpm the voltage was 12.52v . So I guess the alternator is suspect.
If you have an external voltage regulator then suggest you check those connections to ensure they are correct and secure. Not sure what setup you have but the old style arrangement has 3 wires from the alternator marked Field (usually a green wire but not always) Stator and Alternator. The Field and Stator wires run between your alternator and voltage regulator - make sure they are secure and not reversed. The Alternator wire also runs to your voltage regulator, via the starter solenoid and possibly via the ammeter if you have one. Make sure those wires are correct and secure. Your voltage regulator will also have a wire marked Ignition and it runs to your ignition switch. If all these wires look like they are routed right and not loose, then suggest you pull your alternator and take it to Autozone or O'Reillys and they can test it.
Doug R likes this.
Reply With Quote
  #7 (permalink)  
Old 03-19-2017, 04:04 PM
Registered User
Visit my Photo Gallery

 
Join Date: Aug 2012
Cobra Make, Engine:
Posts: 3
Not Ranked     
Default

Thanks
Yes - My setup is the old style with the external voltage regulator and my alternator has three wires so I appreciate the information on the connections.
Reply With Quote
Reply


Thread Tools
Display Modes

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 On
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 10:28 AM.


Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
The representations expressed are the representations and opinions of the clubcobra.com forum members and do not necessarily reflect the opinions and viewpoints of the site owners, moderators, Shelby American, any other replica manufacturer, Ford Motor Company. This website has been planned and developed by clubcobra.com and its forum members and should not be construed as being endorsed by Ford Motor Company, or Shelby American or any other manufacturer unless expressly noted by that entity. "Cobra" and the Cobra logo are registered trademarks for Ford Motor Co., Inc. clubcobra.com forum members agree not to post any copyrighted material unless the copyrighted material is owned by you. Although we do not and cannot review the messages posted and are not responsible for the content of any of these messages, we reserve the right to delete any message for any reason whatsoever. You remain solely responsible for the content of your messages, and you agree to indemnify and hold us harmless with respect to any claim based upon transmission of your message(s). Thank you for visiting clubcobra.com. For full policy documentation refer to the following link: CC Policy