MSD Tech Support Forums

Go Back   MSD Tech Support Forums > MSD Ignition Forums > Trouble-Shooting

Trouble-Shooting Diagnose your ignition

Reply
 
Thread Tools
  #1  
Old 10-03-2012, 10:33 PM
Schurkey Schurkey is offline
Member
 
Join Date: Jan 2012
Location: The Seasonally Frozen Wastelands
Posts: 30
Default Defective Blaster 2 coil

I have a defective Blaster 2 coil. It is ancient; old enough to say "Made In USA" molded into the top.

The coil still makes sparks, but low-voltage; the spark won't jump a proper gap.

Replacing this coil with an even-more-ancient original GM coil restores decent spark--the GM coil will now throw a spark three or five times as far as the defective MSD coil, although perhaps not as far as the MSD coil prior to it becoming defective. There's no question that the MSD coil is currently defective.

My question is: What can cause a coil to lose power yet still be very close to published specs for resistance tests?

Primary resistance of my defective coil: .6 ohms. Published spec is .7 ohm.
Secondary resistance of my defective coil: 4.25K ohms. Published spec is 4.5K ohm.

I'm thinking internal short--the coil windings are OK, but the spark is shorting from windings to the inside of the case of the coil instead of being directed to the coil wire terminal. What do you think?
Reply With Quote
  #2  
Old 10-04-2012, 06:57 AM
msdtech1955's Avatar
msdtech1955 msdtech1955 is offline
Senior Member
 
Join Date: Jan 2008
Posts: 8,838
Default

was it mounted up and down or on its side?
Reply With Quote
  #3  
Old 10-04-2012, 07:34 AM
Schurkey Schurkey is offline
Member
 
Join Date: Jan 2012
Location: The Seasonally Frozen Wastelands
Posts: 30
Default

Mounted up and down...in an MSD spark-testing display.

Spent it's whole life being punished by enormous air gaps while it tried to "make lightning".

Chrysler was good for mounting oil-filled coils on their sides--millions of 440s were set up that way from Mother Mopar. Not me, though.
Reply With Quote
  #4  
Old 10-04-2012, 09:35 AM
msdtech1955's Avatar
msdtech1955 msdtech1955 is offline
Senior Member
 
Join Date: Jan 2008
Posts: 8,838
Default

sounds like a break or short in the internal bobbin .
Reply With Quote
  #5  
Old 10-04-2012, 09:39 AM
Schurkey Schurkey is offline
Member
 
Join Date: Jan 2012
Location: The Seasonally Frozen Wastelands
Posts: 30
Default

Quote:
Originally Posted by msdtech1955 View Post
sounds like a break or short in the internal bobbin .
Are you saying it's not a break or short in the WIRING, but in the (metal?) form the wire is wound on?

I'm tempted to "disassemble and inspect" just for giggles.
Reply With Quote
  #6  
Old 10-04-2012, 12:33 PM
msdtech1955's Avatar
msdtech1955 msdtech1955 is offline
Senior Member
 
Join Date: Jan 2008
Posts: 8,838
Default

it's either arching internal --( bobbin...).or a break in the windings.
bobbin+coil.JPG
Reply With Quote
  #7  
Old 10-04-2012, 03:07 PM
Schurkey Schurkey is offline
Member
 
Join Date: Jan 2012
Location: The Seasonally Frozen Wastelands
Posts: 30
Default

Quote:
Originally Posted by msdtech1955 View Post
it's either arching internal --( bobbin...).or a break in the windings.
Attachment 2472
If I had a break in the windings, wouldn't the ohmmeter show an open circuit?

Thanks for the photo, I wasn't sure what the inside would look like. Have not yet cut the crimped metal band and looked inside.
Reply With Quote
Reply

Bookmarks

Thread Tools

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

Forum Jump


All times are GMT -6. The time now is 08:01 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
2011 MSD Performance