Antique Tractors
[Home] - [HELP] - [Forums] - [Library] - [Photo Gallery] - [Groups] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] -

Go Back   SmokStak > SmokStak® Old Iron and Tractor Community > Antique Steel Wheel Tractors - Old Iron Lugs and Cleats
Forgot Password? Join Us!

Notices

Antique Steel Wheel Tractors - Old Iron Lugs and Cleats Photos and information about antique steel wheeled farm tractors. This is where to find the heaviest of Old Iron tractors.

Antique Steel Wheel Tractors - Old Iron Lugs and Cleats

Magneto Question


this thread has 12 replies and has been viewed 1309 times

Reply
 
Thread Tools Display Modes
  #1  
Old 03-01-2018, 07:30:12 AM
G Willikers G Willikers is offline
Subscriber
 
Join Date: Mar 2006
Location: Canada
Posts: 11,991
Thanks: 11,321
Thanked 27,108 Times in 6,830 Posts
Default Magneto Question

Way back when, we discussed tractor magnetos and grounding out spark plug wires that were not being used, such as when using a 4-cylinder mag on a 2-cylinder engine.
A friend is working on a mag for another friend right now. It is a 4-cylinder Robert Bosch for a Hart Parr. Bosch has looked after the unused leads. He says there is an "air gap" where you can see the spark being made.
His question is, is it better to allow the unused wires to make a spark somewhere, or does it do just the same thing to simply take them direct to ground.
Do they need to make an actual spark for the betterment of the coil, etc.?
Thank you for any thoughts.
Reply With Quote
Sponsored Links
  #2  
Old 03-01-2018, 08:25:17 AM
Kelly Tytlandsvik Kelly Tytlandsvik is offline
Subscriber
 
Join Date: Aug 2005
Location: Estevan, Saskatchewan Canada
Posts: 1,131
Thanks: 228
Thanked 3,568 Times in 454 Posts
Images: 407
Default Re: Magneto Question

Hi G

My understanding is the wider the gap the more the coil has to put out and greater the chance of it shorting out the coil. So by having a gap something along the lines of what the spark plug would have would make the coil put out the same as when it is connected to a plug. If the unused terminals are left open or ungrounded then the coil will be forced to put out higher voltage and risk ruining the coil. If the terminals are grounded the current will have a place to go and the coil will put out less voltage therefore saving the coil.

I think with the magneto you are talking about must have been a flavour of the day??????? Not sure but grounded or gapped would still keep from damaging the coil.

I think I just babbled and wasn't much help????

Kelly T
Reply With Quote
The Following User Says Thank You to Kelly Tytlandsvik For This Post:
  #3  
Old 03-01-2018, 08:40:21 AM
Kirk Taylor Kirk Taylor is offline
Registered-II
 
Join Date: Nov 2004
Location: Bedford, PA
Posts: 784
Thanks: 0
Thanked 499 Times in 284 Posts
Default Re: Magneto Question

Quote:
Originally Posted by G Willikers View Post
Way back when, we discussed tractor magnetos and grounding out spark plug wires that were not being used, such as when using a 4-cylinder mag on a 2-cylinder engine.
A friend is working on a mag for another friend right now. It is a 4-cylinder Robert Bosch for a Hart Parr. Bosch has looked after the unused leads. He says there is an "air gap" where you can see the spark being made.
His question is, is it better to allow the unused wires to make a spark somewhere, or does it do just the same thing to simply take them direct to ground.
Do they need to make an actual spark for the betterment of the coil, etc.?
Thank you for any thoughts.
G W,
Kelly is correct. The "spark that you see being made" is a safety gap in case a wire happens to get disconnected. It was never intended to operate continuously. The voltage required to jump the safety gap is significantly higher than that required to jump the spark plug, otherwise it would cause misfires. Forcing the safety gap to conduct puts a lot of voltage stress on the coil. The fact that it's now a nearly 100-year-old coil is not in your favor.

Kirk
Reply With Quote
The Following User Says Thank You to Kirk Taylor For This Post:
  #4  
Old 03-01-2018, 10:36:42 AM
9 hp Alamo 9 hp Alamo is offline
Registered
 
Join Date: Mar 2017
Location: Owendale, Michigan
Posts: 19
Thanks: 31
Thanked 49 Times in 15 Posts
Default Re: Magneto Question

My father has a 18-36 Hart Parr that has a four cylinder Fairbanks mag on it, and those wires are directly grounded; bolted to the mounting bracket. As far as we can tell that mag has been on there for a good 50+ years and we've never has any trouble with it, or heard of the previous owner having trouble.
-Good luck
Reply With Quote
The Following 2 Users Say Thank You to 9 hp Alamo For This Post:
  #5  
Old 03-01-2018, 01:26:31 PM
Andrew Mackey Andrew Mackey is offline
Sponsor
 
Join Date: Nov 2004
Location: Rockaway, New Jersey USA
Posts: 13,233
Thanks: 1,843
Thanked 6,052 Times in 3,942 Posts
Exclamation Re: Magneto Question

The un-used ignition terminals should be grounded in order to reduce excess stress on the coil. As others have noted, to use the safety gap built in, is not a good idea. Also - do not use resister (modern carbon core) wire on a magneto. Too much rsistance will damage the coil.
Reply With Quote
The Following 2 Users Say Thank You to Andrew Mackey For This Post:
  #6  
Old 03-01-2018, 02:48:12 PM
Ken Majeski's Avatar
Ken Majeski Ken Majeski is offline
Subscriber
 
Join Date: Oct 2004
Location: South Lawton, Wisconsin
Posts: 2,802
Thanks: 1,572
Thanked 2,402 Times in 831 Posts
Images: 46
Default Re: Magneto Question

How about the Bosch DU 4/2 mags used on the lightweight Rumelys ? Seems like they have this Little Gizmo connected to 2 terminals.

Frankly I think it makes little difference if you ground the unused wires or use a spark gap as long as it's not too wide. But something about a Extra unshielded spark around an engine that is already loaded with Hot oil and Gas Fumes don't exactly give me a Warm Fuzzy Feeling
__________________
Ken Majeski, Ellsworth Wis.

Last edited by Ken Majeski; 03-01-2018 at 03:42:33 PM.
Reply With Quote
The Following 2 Users Say Thank You to Ken Majeski For This Post:
  #7  
Old 03-01-2018, 09:01:32 PM
halcon halcon is offline
Registered-III
 
Join Date: Feb 2010
Location: Fillmore, Saskatchewan, Canada
Posts: 1,172
Thanks: 2,499
Thanked 1,858 Times in 817 Posts
Default Re: Magneto Question

Those gizmos are flame arresters-----fear not.
Reply With Quote
  #8  
Old 03-01-2018, 09:31:38 PM
Jon Nessel's Avatar
Jon Nessel Jon Nessel is offline
Subscriber
 
Join Date: Sep 2007
Location: Chilliwack B.C. Canada
Posts: 600
Thanks: 811
Thanked 1,015 Times in 284 Posts
Default Re: Magneto Question

Going from memory, the DU4/2's safety gap is adjustable.
Reply With Quote
  #9  
Old 03-01-2018, 10:50:44 PM
Oilpulled Oilpulled is offline
Subscriber
 
Join Date: Jun 2008
Location: Rockford, Illinois, USA
Posts: 3,997
Thanks: 10,988
Thanked 5,563 Times in 2,145 Posts
Default Re: Magneto Question

Most high tension magnetos have a safety gap which is under the porcelain insulator in Bosch Du-4 and KW and others. The IHC E4 & F4 Have it inside. The Bosch DU4-2 has a little one on the outside of the distributor cap for the two unused outputs. The gap is usually protected with a fine screen. When grounded (shorted) or with a safety gap, the voltage induced in the secondary is all or mostly dropped by the coil's internal impedance and is not developed. If allowed to operate at open circuit, the full voltage will be developed and may jump between turns of wire in the secondary eventually destroying it. There are 10,000 to 20.000 turns of wire. The dielectric strength of the secondary insulation on the wire and between the turns of wire protect it. However magnetos with a varnish which contains solvents as in years past will have voids where the solvent evaporated from and will not be protected as well as those with vacuum impregnated insulation varnish without solvents to evaporate. The dielectric strength is very important in high voltage applications.
Reply With Quote
The Following 3 Users Say Thank You to Oilpulled For This Post:
  #10  
Old 03-01-2018, 10:54:24 PM
Ken Majeski's Avatar
Ken Majeski Ken Majeski is offline
Subscriber
 
Join Date: Oct 2004
Location: South Lawton, Wisconsin
Posts: 2,802
Thanks: 1,572
Thanked 2,402 Times in 831 Posts
Images: 46
Default Re: Magneto Question

Yup Clyde, Plus the fact that the wasted sparks are inside the Die cast Mag Cover if it hasn't disintegrated and Fell Off.
__________________
Ken Majeski, Ellsworth Wis.

Last edited by Ken Majeski; 03-01-2018 at 11:06:24 PM.
Reply With Quote
The Following User Says Thank You to Ken Majeski For This Post:
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 Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
IHC L magneto question. Barry Chorum Antique Gas Engine Discussion 2 08-22-2014 08:48:47 PM
Magneto Question 1937witte Magnetos, Ignition Coils and Spark Plugs 1 11-11-2010 04:49:01 PM
IHC M Magneto Question Tom Martin Antique Gas Engine Discussion 10 02-21-2007 09:19:16 AM
Magneto Question Rich Martz Antique Engine Archives 2 05-26-2004 01:02:19 AM
Magneto Question Tom Wahl Antique Engine Archives 2 06-05-2002 12:39:54 AM


Use "Ctrl" mouse wheel to change screen size.
All times are GMT -4. The time now is 04:19:47 AM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark - A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2016 by Harry Matthews P.O. Box 5612 - Sarasota, FL 34277