Anyone know how to test a magneto? - Pirate4x4.Com : 4x4 and Off-Road Forum
 
Pirate4x4.Com : 4x4 and Off-Road Forum  

Go Back   Pirate4x4.Com : 4x4 and Off-Road Forum > General Tech > General 4x4 Discussion
Notices

Reply
 
Share LinkBack Thread Tools Display Modes
Old 03-15-2002, 09:51 PM   #1 (permalink)
 
Join Date: Apr 2001
Member # 4288
Posts: 152
Anyone know how to test a magneto?

I am a bit out of my depth here - sorry for the off-topic post. I crew on a sprint car, mainly carrying heavy things and such but with our crew chief out of town we are stuck with no spark. It is a very simple system, a Mallory mag and coil. The mag has a two-wire hookup and plain old points.

We are not getting any spark. Diagnosing this thing is pretty foreign compared to standard ignition systems, in that there is no current flowing through anything when it is not running. It appears that the magneto charge the coil when the points are open, and current from the mag is grounded when the points close.

The engine is shut down by grounding the + terminal on the coil. Unfortunately it seems like we are getting a ground from just about everywhere - mag body, points open, points closed, both sides of the coil, etc.. These things are voodoo compared to a std ignition system.

Web search shows me install diagrams for the mag and timing setting using a buzz box, but no diagnostic steps.

Any help appreciated

thanks

Brian
yurtle is offline   Reply With Quote Quick reply to this message
Old 03-16-2002, 03:47 PM   #2 (permalink)
Registered User
 
Join Date: May 2000
Member # 800
Location: petawawa ontario
Posts: 524
I would first check to make sure your points are not shorted to ground anywhere, then make sure they are opening and closing properly. you should be able to give the thing a good spin by hand and get some kind of spark out of it.
__________________
my dodge sucked, I went superduty
mytzlflick is offline   Reply With Quote Quick reply to this message
Sponsored Links
Old 03-16-2002, 07:33 PM   #3 (permalink)
 
Join Date: Jun 2001
Member # 5495
Posts: 146
Grab the leads and have someone spin it for you. If your hair stands up, it works. if not, than she broken.
Johncm is offline   Reply With Quote Quick reply to this message
 
Old 03-16-2002, 09:52 PM   #4 (permalink)
Registered User
 
Join Date: May 2001
Member # 4783
Location: Orange Co. CA
Posts: 1,729
I have never seen a magneto with points, but if there is no battery voltage at the coil, then it must be one. The only obvious reason to have points would be to vary the timing. The coil shouldn't be grounded with the points open. Do you have two coils so that you can compare it with a good one?
Pin Head is offline   Reply With Quote Quick reply to this message
Old 03-16-2002, 11:12 PM   #5 (permalink)
Registered User
 
Join Date: Apr 2000
Member # 695
Location: NorthWest AR
Posts: 811
Im pretty drunk ,so dont listen too hard.

I THINK the points are normally closed ( touching) and when they open that drops the primary on the coil and induces the secondary , viola ya got magnetic induction.

adjust that point gap, and give it a go.

No idea what it should be, if I had to guess Id start at 0.030
__________________
too small to be seen, and too big to control, and treated like a walking bomb...
ozarkjeep is offline   Reply With Quote Quick reply to this message
Old 03-16-2002, 11:44 PM   #6 (permalink)
TR
Zeus of the Sluice
 
TR's Avatar
 
Join Date: Jan 2001
Member # 2877
Location: Orange, Va
Posts: 4,549
man ozark you hit the nail on the head, ever tired to go to work drunk and see if you do any better?
__________________
Penn State study finds that heavy drinking is 100% easier than giving a shit
TR is online now   Reply With Quote Quick reply to this message
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Pirate4x4.Com : 4x4 and Off-Road 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.

** A VERIFICATION EMAIL IS SENT TO THIS ADDRESS TO COMPLETE REGISTRATION!! **

Email Address:
Insurance
Please select your insurance company (Optional)

Log-in


Thread Tools
Display Modes

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



All times are GMT -7. The time now is 05:03 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.0 ©2011, Crawlability, Inc.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.