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SAM86

H4 Magneto Impulse Assembly

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Does anyone still make new Impulse assemblies for the H4 magneto's? Could have sworn these were still available but no luck finding one. Rebuilding the mag for my brothers C, dogs are badly worn eating into the housing snd screws. Parts mag is in even worse shape. 

Go figure the one good replacement I have is for the Continental engine so the keyway is in a different location.

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Very good post question, Ive never worked on any of mine , very interested in the responses. 
Do you use the tractor house parts search ? If you do put the part numbers into that parts search and see what comes up ? I’m sorry only help I gots ! 🤷‍♂️👀

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Not know where exactly , if all else fails I have rebuilt the parts with weld or most often with brace and remachine them !

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I just had mine apart the other day and mine was just fine. New coil and condenser.

That pin the dog runs up against is really hard but I assume it can wear and also work loose in the case.

Those are only used on start and do not hit while running.

I looked on eBay and no impulse parts or just cases.

$85.00 for a used one. It appears a used one will be your only option.

 

 

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I am certainly not a magneto expert but I have worked on quite a few. I have never seen one worn as much as you described. I would think you could find a good used one to replace it with. I have to think that your’s may not have been disengaging correctly. As DD stated above, it should not be clicking except when starting the engine. If engaged while running, it would cause excessive wear. 

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I think the previous post misled where I was describing the wear problem. The dogs catching the trip pin is not the location where I am describing. The dogs are worn on the pins they pivot on allowing excessive tilt (when viewed from the side) of the dog. This is allowing the dogs to eat into the mounting flange and the four screws that hold the mounting flange onto the magneto housing. The attached images should help.

53E8520E-41AA-4DA0-B4AD-9037E5979238.jpeg

B226ED56-5138-4D44-BA59-E0E69AEFEBF4.jpeg

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Now I see what is happening here.

Where is the wear?

Is it in the pins, or in the fly weights, or both?

Take it apart one more step and send a photo?

The case will still work fine but you want this grinding stopped.

 

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8 minutes ago, Diesel Doctor said:

Now I see what is happening here.

Where is the wear?

Is it in the pins, or in the fly weights, or both?

Take it apart one more step and send a photo?

The case will still work fine but you want this grinding stopped.

 

 

        What Diesel Doctor said is very accurate,   I would suggest that you try  to tighten the pivots for the flyweights by  re-riveting them.  They may well tighten up just fine by tightening the rivets on an anvil.   If they do that will be an easy fix,  if they don't you have lost nothing.  

       Hope this works.

GT&T

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I’m learning a lot from your post ,please show me a end wrench view of weights pivot,  I assumed the weight needs a attention somehow to hold it perpendicular to the rotation 

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On 7/3/2020 at 9:20 AM, GT&T said:

 

        What Diesel Doctor said is very accurate,   I would suggest that you try  to tighten the pivots for the flyweights by  re-riveting them.  They may well tighten up just fine by tightening the rivets on an anvil.   If they do that will be an easy fix,  if they don't you have lost nothing.  

       Hope this works.

GT&T

GT&T, pretty sure the pivot pins for the dogs are welded in. Tried to remove the set out of the Continental impulse and it cracked pretty easy. I'm not 100% sure they are welded, but on all of the ones I have the pivot pins sit below flush on the reverse side making me question if they are rivited in.

On 7/3/2020 at 10:24 AM, mmi said:

Thanks mmi. Just bough another core mag and the impulse is worse than this one. Gonna hold off on buying more unless I can inspect them first.

11 hours ago, 560Dennis said:

I’m learning a lot from your post ,please show me a end wrench view of weights pivot,  I assumed the weight needs a attention somehow to hold it perpendicular to the rotation 

560, I needed to get this one going and out of the way for now so I need to revisit the impulse later. From what I visually saw, no appreciable wear marks on the bore of the dogs although there should be from tge amount of movement there is. The pivot pins very obviously very worn at the top compared to the good continental impulse I have. If you haven't seen one of these apart the pivot pins are hourglass shaped. The bearing surface of the pin is limited to two small landings top and bottom. For a quick fix I ended up adding two sets of shims instead of one set under the retainer clips holding the dogs on. 

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1 hour ago, SAM86 said:

GT&T, pretty sure the pivot pins for the dogs are welded in. Tried to remove the set out of the Continental impulse and it cracked pretty easy. I'm not 100% sure they are welded, but on all of the ones I have the pivot pins sit below flush on the reverse side making me question if they are rivited in.

Thanks mmi. Just bough another core mag and the impulse is worse than this one. Gonna hold off on buying more unless I can inspect them first.

560, I needed to get this one going and out of the way for now so I need to revisit the impulse later. From what I visually saw, no appreciable wear marks on the bore of the dogs although there should be from tge amount of movement there is. The pivot pins very obviously very worn at the top compared to the good continental impulse I have. If you haven't seen one of these apart the pivot pins are hourglass shaped. The bearing surface of the pin is limited to two small landings top and bottom. For a quick fix I ended up adding two sets of shims instead of one set under the retainer clips holding the dogs on. 

I don’t happen to have my blue ribbon magneto repair manual ,at the farm . I was wondering why the wear in photo s . ,a way looks like about .03 inch . So the weight don’t seem to be worn , that’s what’s confusing me. I’m don’t have any idea withOut  a schematic. 

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