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mdm1 
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Joined: 12 Sep 2009
Location: Onalaska, WI
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 Topic: Magneto ?
Posted: 24 Aug 2024 at 10:09am |
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I have a B with a FMJ mag on it with battery start. I pulled the mag to clean it up and found the springs on the dogs (weights) were not hooked up. It appears they have been like that for some time. The motor did run. I tried to hook them up but they are in tuff shape. It will spark but really weak snap. What's the worst that could happen if they are not hooked up to the weights? It will start and run. I am looking for an impulse coupler. Any help appreciated.
Edited by mdm1 - 24 Aug 2024 at 10:17am
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Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK!
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dfwallis
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Joined: 09 Mar 2023
Location: DFW
Points: 631
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Posted: 24 Aug 2024 at 2:25pm |
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If referring to the weights commonly used for retarding (/advancing) timing, often the range of control is limited. I would think that given the typical design of retarding timing at higher RPM, and without the springs the weights are likely to fly apart prematurely, and it will just result in timing being retarded at low RPM. For best performance, the springs should be attached (assuming the weights are intact and free to move). I looked at various FM magneto internal diagrams and didn't find one with such weights. I'm just guessing based upon a common distributor mechanism.
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1952 CA13092
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WF owner
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Joined: 12 May 2013
Location: Bombay NY
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Posted: 24 Aug 2024 at 3:25pm |
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The old (now deceased) guy that worked on my mags for years told me that the impulse was less critical with the tractors I was using a 12 volt battery to start. He said the impulse was very important for hand cranking and 6 volt systems that turned over slow.
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mdm1
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Joined: 12 Sep 2009
Location: Onalaska, WI
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Posted: 24 Aug 2024 at 4:32pm |
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That's what I kinda thought. It's 6v now but needs a battery. May just convert to 12v.
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Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK!
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steve(ill)
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Joined: 11 Sep 2009
Location: illinois
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Posted: 24 Aug 2024 at 7:00pm |
I had one with WEAK SPRINGS... It didnt grab, to wind up the IMPULSE, very well if at all. That makes the engine try to start at 30 degrees BTDC, the running FIRE mark... NOT GOOD.
The springs allow the impulse to WINDUP, then SNAP at TDC for starting..
Edited by steve(ill) - 24 Aug 2024 at 7:10pm
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Like them all, but love the "B"s.
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steve(ill)
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Joined: 11 Sep 2009
Location: illinois
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Posted: 24 Aug 2024 at 7:04pm |
I looke EVERYWHERE for spring and / or an impulse complete... NO CAN DO...
I ended up seeing one of the vendors "selling out" of his rebuild stock on this stie and i bought a GREAT REBUILT MAG....I used my "other" unit as spare parts... but no springs.
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Like them all, but love the "B"s.
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Alberta Phil
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Joined: 13 Sep 2009
Location: Alberta, Canada
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Posted: 24 Aug 2024 at 7:35pm |
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Steve at B&B can probably fix you up. He's on here pretty well daily and works on those mags.
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Dakota Dave
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Joined: 12 Sep 2009
Location: ND
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Posted: 25 Aug 2024 at 1:07am |
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I just got all the parts for my mag from brillman. The only spring in a fmj is the flat spring in the impulse coupler. My CA has been hard starting for a long time. I rebuilt the mag and now it starts on the first compression stroke.
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mdm1
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Posted: 25 Aug 2024 at 3:26am |
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Both of mine have small springs on the dogs plus the flat spring. I'm checking with some people now. Looked at Steve"s webpage and he does have one. Going to replace it.
Edited by mdm1 - 25 Aug 2024 at 3:35am
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Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK!
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steve(ill)
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Posted: 25 Aug 2024 at 7:31am |
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The BIG impulse wind up spring is available... The DOGS are available.. Its the LITTLE two springs and the IMPULSE case inself that are VERY HARD to come by.
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Like them all, but love the "B"s.
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mdm1
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Posted: 25 Aug 2024 at 7:41am |
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Steve that is what I am finding out.
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Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK!
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mdm1
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Posted: 25 Aug 2024 at 5:14pm |
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Found a nos impulse coupler. Got it ordered.
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Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK!
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jvin248
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Joined: 17 Jan 2022
Location: Detroit
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Posted: 25 Aug 2024 at 9:03pm |
 steve(ill) wrote:
The BIG impulse wind up spring is available... The DOGS are available.. Its the LITTLE two springs and the IMPULSE case inself that are VERY HARD to come by. |
Any specs on those little springs? Find matches on McMaster-Carr? Wire size and spring dia, length can get there.
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Matt (Jordan,MN)
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Joined: 12 Sep 2009
Location: Jordan, MN
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Posted: 26 Aug 2024 at 12:27pm |
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The little spring on the stop pawls where a later addition. Many of the FMJ mags did not have them so they are not required. I did try to order them, but they are discontinued. The reason a pawl skips past the stop is that it is worn. it doesn't take much wear to make them skip past. I have built them up in the past. Another common problem is the pawl pins that hold the pawls in place become loose in the pawl plate. If your mag has weak snap that means someone has been in it and didn't wind the spring up sufficiently or the spring is broke. it takes one full turn on a UA or UB series drive couplings.
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Owner of Matt Scott LLC
Specializing in NOS and used Allis Chalmers tractor & implement parts & liturature and Magneto Repair
http://www.mattscottllc.com/
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mdm1
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Posted: 26 Aug 2024 at 12:44pm |
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Thanks to everyone. I have heard that the springs are not needed from a few rebuilders now. I believe I need a new impulse coupler anyway. Will keep this one for parts.
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Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK!
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dfwallis
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Posted: 26 Aug 2024 at 1:44pm |
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Springs are a commodity item, especially plain straight springs. If you can get the wire diameter, spring diameter, and spring length, you can likely get them at a local hardware store or order online. It's going to be pretty darn close if you have those characteristics correct.
Edited by dfwallis - 26 Aug 2024 at 1:46pm
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1952 CA13092
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