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steve(ill) 
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 Topic: Magnito Impulse
Posted: 07 Aug 2023 at 8:17pm |
Anyone got a good way to TEST this ?
Have a B wtih mag and 12v system. Use to start for 10 years on 1-2 revolutions of the motor.. Last year, it would not start one day.. Removed the mag and installed new condenser and point. Tested on bench 10 times. Fires good.. Put on tractor, no start.. Back on bench works OK... on tractor, no start................ Installed a SPARE mag and fired right off... PROBLEM SOLVED !
12 months later, happens again... Motor spins FAST for 10 seconds, then you hear it FIRE and starts up.. Good idle, good power... just hard start..... Should not be carb as it was rebuilt ( due to pluggage) 2 months ago.. Mag works GREAT after it starts... Problem is it just has a hard time to FIRE OFF......... Wondering if the impulse has a problem and trying to start in ADVANCE position ? ............. Same problem maybe last year ??
Dont know of a good way to TEST the impulse or what speed it kicks out ? Like i said, it ran GREAT for the last 10 years on 12v with a mag.
anybody ever MODIFY or REBUILD an impulse ? Statically it works OK.
Edited by steve(ill) - 07 Aug 2023 at 8:19pm
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steve(ill)
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Posted: 07 Aug 2023 at 8:22pm |
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anyone ever mess with new springs ? heavier springs ? lighter weights ? ...... im just GUESSING..
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SteveM C/IL
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Posted: 07 Aug 2023 at 8:26pm |
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You are the answer man....sounds like may be turning fast enough to disengage impulser. Can you hear it clicking while cranking?
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MACK
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Posted: 07 Aug 2023 at 8:44pm |
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12V spins them too fast for impulse to work, so it is starting at full advance. MACK
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steve(ill)
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Posted: 07 Aug 2023 at 8:45pm |
my hearing is not good enough to hear a click unless setting on the bench... Remember, this worked for 10 years.. Only recently had the problem...... I just watch a You Tube video of RACHEL rebuilding a mag with NEW springs and NEW weights.. She had a 1 revolution windup on the spring when installed. Cant say as i really remember that part, but its been running for a year....
Guess i will take the impulse off LAST YEARS mag and check the spring and dogs ( weights).... never considered buying new parts........ dont know for sure thats even the problem..
Edited by steve(ill) - 07 Aug 2023 at 8:46pm
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SteveM C/IL
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Posted: 07 Aug 2023 at 8:47pm |
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Put a big a$$ resistor in cable to starter to slow it down....
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steve(ill)
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Posted: 07 Aug 2023 at 8:50pm |
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I dont think it would start at 30 degrees advance... It HAS been starting on 1 revolution for the past 10 years.
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WF owner
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Posted: 08 Aug 2023 at 6:27am |
I am going to ask a bunch of questions. Have you had the mag apart and, if you have, are you sure the mag is timed right internally? One tooth off can affect starting, even if it appears to have good spark.
Have you had mag off the tractor? Are you sure you are firing on the compression stroke?
Have you tried pull starting it? |
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steve(ill)
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Posted: 08 Aug 2023 at 8:02am |
The tractor has been running for a year with this mag. Just started to be "hard starting". Once it does fire off it run great, plenty of power, good idle, good top RPM... That makes me think "the timing" is off for cranking......... I dont know, but what if the spring in the mag was broken.. seems like i would get NO WIND UP and therefore not fire at TDC, but at the FIRE mark..
This is what it ACTS LIKE... I have not removed for inspection.. I have another mag that was doing similar last year.... Im going to remove and inspect the IMPULSE and SPRING instead of normally working on the Condenser and Coil..........
Just wondering if anyone had similar experience... any modifications to do... spring gets weak ? ...... i know a 12v will spin it faster than a 6v... just thought there might be some MODS to help that......... It has run 10 years on 12v... that has not changed.
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IBWD MIke
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Posted: 08 Aug 2023 at 8:37am |
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I'll have to pile on with the rest, it's just spinning too fast. Went through this with Grandpa's WD. Converted her to distributor, all good.
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steve(ill)
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Posted: 08 Aug 2023 at 12:41pm |
Well, had some success this morning... Basically EVERYONE is right. I have heard for years that a mag impulse will not work on 12v because is spins too fast.. Others have had good luck with the mag on 12 v ... WHY ?
I took the mag off and tried to "SPIN" the impulse with my hand. It should only turn 180 degrees and then the DOG catches on the impulse and you have to wind up the BIG SPRING.. What i found is i could try to SPIN the impulse and about 1/3 of the time it did not catch, or went a full revolution and then would catch.
Took the impulse off the mag and looked at the weights (dogs) that fly out under centrifigual force. They were not firmly seated against the center stop. I could SHAKE the impulse in my hand and watch the weights bounce around ! ??? Most of you know, but for those that do not, the impulse and DOGS work like a rotor on a distributor. As you spin it, the weights fly out for timing advance. Springs hold the weights in a no speed or LOW speed. My springs were obviously SHOT / WEAK.
I had an old FM mag of an International that i could not use because the impulse was TIMED different than on an Allis. I took the impulse off that mag and noted the weights were SMALLER and the springs were TIGHTER.. WHY ? ....
I took the two small springs off the International mag impulse and put them onto my Allis mag impulse... I shook it and they did not move. I mounted the impulse in the drill press and spun it about 300 rpm and i could see the Weights move OUT , pulling on the springs.. Put the mag back on the tractor and it FIRED UP on ONE revolution like it has been doing for the last 10 years..
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SUMMARY ...... OLD springs can get weak and not hold the impulse retarded so the mag will fire at TDC..... NEW springs can fix that.... What i dont know is if there are DIFFERENT springs for some FM mags ? Did any International ever use a 12v system with a FM Mag ? If so, they might have had stronger springs.... Physically the springs dont look much different, just a little stronger..
Will post photos after lunch... Im happy ! ... Thanks to all for the discussion.. Just needed someone to bounce a few ideas off of to get some new ideas.
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steve(ill)
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Posted: 08 Aug 2023 at 12:55pm |
https://www.youtube.com/watch?v=2fmnP700qXc
if you have never watch this video of Rachel, you should. I hate to admit that i learned somethings that i did not know about mags from a 20 year old girl.
When you install the impulse, she says to wind up the BIG SPRING 1 full turn. I think i normally have done 1/2 turn...... and she looks at the WEIGHTS and SPRINGS and says to "BUY NEW" .... I have always just glanced over the impulse to see that the weights were free to move about.. NEVER considered the spring tension as being important.
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SteveM C/IL
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Posted: 08 Aug 2023 at 1:18pm |
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Soooo...old dogs can learn new tricks.
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steve(ill)
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Posted: 08 Aug 2023 at 9:21pm |
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IBWD MIke
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Posted: 09 Aug 2023 at 9:04am |
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Interesting post Steve. Both of my WD's came with mag's and I converted them to distributors. Still have the original mags for them, might be hope to putting them back someday? Might even change Grandpa's back to six volt and generator. It's buried in the shed and doesn't get out much, would be nice if it were all original.
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steve(ill)
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Posted: 09 Aug 2023 at 12:35pm |
I dont know if there are "stronger springs" that you can get off of some other mags or not.. Dont know if a mag was ever "factory" on any 12v system that might spin faster..
What i do know is my 70 year old springs were SHOT... If i ever need a set, i think im going to break down and call Rachel for a new unit..
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Les Kerf
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Posted: 10 Aug 2023 at 8:09am |
This good stuff 
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HudCo
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Posted: 10 Aug 2023 at 9:46am |
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i would like to know if their is a better springs my wd spins to fast for the impulse to work but it starts good , steve you may have some blockage in the carb could just have a few drops of water down in the bowl , may be developed a vaccumm leak could also be time to check the valve lash
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steve(ill)
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Posted: 10 Aug 2023 at 9:53am |
Put the mag back on the tractor and it FIRED UP on ONE revolution like it has been doing for the last 10 years..
I think this is the tell - tale.. as a "test" to rule out some things.. i checked compression to be 100 psi on all cylinders.. and i loosened the inlet hose on carb and shot ether in ... no pop/start.... i had checked timing twice and spark when hand cranking and all was good ... thats when i pulled the mag for the third time to check the impulse.
Edited by steve(ill) - 10 Aug 2023 at 10:00am
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WF owner
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Posted: 11 Aug 2023 at 6:07am |
I asked before, but you never answered. Does it start easily when pull-starting it? Putting it in high gear and towing relatively slowly should turn it over slow enough for the impulse to work.
I have a WD with a mag on it. I have had a 12 volt battery in it for years. The impulse "click" is very easy to hear when cranking. The tractor always starts very quickly, turning over only a couple times or less.
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steve(ill)
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Posted: 11 Aug 2023 at 8:19am |
Put the mag back on the tractor and it FIRED UP on ONE revolution like it has been doing for the last 10 years..
Tractor would not start... Pulled MAG and changed the springs on the impulse weights. Reinstalled and STARTS ON ONE REVOLUTION.... SPRINGS on the IMPULSE are the problem.. Was trying to start at FULL ADVANCE.
Ii have no way to pull start with one person. Not a fix anyway.. I had gas, i had spark, i had compression, i had air....what i did NOT have was correct timing at TDC because of the impulse.
Edited by steve(ill) - 11 Aug 2023 at 8:21am
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Les Kerf
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Posted: 11 Aug 2023 at 9:11am |
 WF owner wrote:
...I have a WD with a mag on it. I have had a 12 volt battery in it for years. The impulse "click" is very easy to hear when cranking... |
The WD is a different animal than Steve's B; the obvious difference is a significantly bigger engine, but somewhat less obvious is the smaller gear in the starter drive on the WD. Simply stated, the WD starter will spin its engine slower than the B. The starters are electrically the same, just clocked differently; in fact, I converted a WD starter to use on my currently owned C by rotating the nose cone and doing some careful drilling. I used to own a Model C that I converted to 12 volts; it most definitely spun the engine too fast, the impulse would not engage until the starter was disengaged and as the engine slowed down you could hear the mag click and it would fire up instantly. You could spin that engine on the starter for long periods and it WOULD NOT FIRE UP until you released the starter. That starter was so violent that it broke several starter drives and finally chewed up the ring gear on the flywheel. After replacing the ring gear I converted it back to 6 volts (yup, I'm a slow learner). Much thanks to Steve for sharing this knowledge, and also for the link to Rachel's video (that lady is something special!)
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HudCo
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Posted: 11 Aug 2023 at 9:20am |
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les was you using a 12v starter or running a 6v starter on 12v , a 12v starter on 12v will smooth
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Les Kerf
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Posted: 11 Aug 2023 at 9:47am |
HudCo wrote:
les was you using a 12v starter or running a 6v starter on 12v , a 12v starter on 12v will smooth |
That was a 6V starter that was breaking the starter drives on 12 V; the starter I am now running on my current Model C is also a 6V running on 12 V with no problems. Various board members here have reported similar results; for unknown reasons, some 6 Volt starters spin violently on 12 Volts, some seem to do fine. No one on this forum has been able to definitively prove why.
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steve(ill)
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Posted: 11 Aug 2023 at 9:55am |
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If you get GOOD springs on the impulse, and have the motor tuned up right... motor will start in a couple revolutions and not have time to get up to the speed of throwing the impulse weights outward ............ that could be the difference ?? Mine does spin VERY FAST with the ignition off.... but it does start in a revolution or two when ignition on.
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Les Kerf
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Posted: 11 Aug 2023 at 10:12am |
steve(ill) wrote:
If you get GOOD springs on the impulse, and have the motor tuned up right... motor will start in a couple revolutions and not have time to get up to the speed of throwing the impulse weights outward ............ that could be the difference ?? Mine does spin VERY FAST with the ignition off.... but it does start in a revolution or two when ignition on. |
Yup, this thread has been most enlightening for me; I am confident that my engine was tuned properly, it just wouldn't get a good, properly timed spark when the engine was spinning fast enough to disengage the impulse.
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