Wico Model C mag

[Anonymous-0]

Have a Wico C in for repair and am unable to get any fire. Have done the following---Coil checks OK. Condensor checks OK. Points are set correctly. Short wire between caps replaced and ends soldered. All points of contact cleaned. Have had it apart about 5 times and double checked and triple checked my work and still no spark. Any ideas?? No cracks in either cap. Thanks in advance. jim

 

[greenmech]

I would replace the condenser and check continuity on the plug posts to the inside contact point.Is the points holder grounded? Ron Mn.

 

[Anonymous-0]

Checked continuity like you suggested and all is OK. Should the point block be grounded?? As far as I know, it is metal to metal. Thanks. jim

 

[greenmech]

I believe its grounded to the main case at two points.How about the coil wire,make contact to the coil to terminal? Ron Mn.

 

[John T]

James, heres a couple problems in those C Mags that can cause spark failure.

1) Be sure the spring on the points isnt shorting up against the pin. Sometimes its necesary to grind off a lil piece of the end of the spring so it doesnt short out the points.

2) There are a couple lil springy contactors that cause the points plate to get a ground with the rest of the case, sometimes they need bent or the case needs cleaned where they mate up the points plate to the back portion of the case.

You need to put a good ohm meter on the R x 1 scale on the points and case ground and insure when the points are open theres like .5 ohms to ground which represents the coils primary but when they are closed it needs to go to near zero ohms assuming the points plate has that good ground to case as noted above.

Make sure the condensor is okay and NOT a short

Make sure both the coil ground leads (primary and secondary) have a good ground where the 2 lil ground wires bond to the case.

The coils primary is around .5 to .7 ohms while the secondary is in the 5 k to 7 k range, check both..

Of course, shes never gonna fire at cranking speed unless the impulse assembly all works and she winds the spring and it snaps n releases IS THE IMPULSE WORKING?????????

See if shes firing out the coils HV output at least in case theres a problem in the cap rotor brush assembly. The coil should fire each time the impulse snaps which is every 180 degrees

Let us know what you find

John T
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[M.Shelby]

IF your C mag has the kill wire option, could it be shorting out? Does the armature still have magnetism? Can you get a spark directly out of the top (coil) nipple; leaving the small cap off for a test? Does the impulse have good strong snap? M.

 

[Anonymous-0]

Thanks to everyone who took their time to answer. Coil wire makes good contacts are good and clean. Have not checked spring on points for short to pin. Will also check the 2 contact points in the cap, did not think to do that. There in no kill wire. Impulse is good and strong, unless I need to wind the spring another turn. Will also check with my ohm meter and thanks for the proper reading. Have rebuilt some other mags, but the Wico C seems to have me stumped, at least for now. Points were also cleaned with alcohol along with my hands before assembling. Their is not one hint of a spark, as I have been holding onto the plug wires with my hand while snapping the impulse. Once again thanks to all and will let you know what I find. jim in ILL

 

[Dick L]

Have you checked how strong the magnets are?

If the magnets are not strong enough it will not build enough electricity to cause a spark. The impulse spring causes the armature to spin at the time the points are to open and close. A weak, broken or improperly wound spring will cause a lack of electricity.

That is the difference between a magneto and a distributor. The magneto makes its own electricity and the distributor has to have its electricity supplied from a battery.

I repaired a FMJ magneto a coupla weeks ago that both sets of magnets had only a slight pull on a large screwdriver bit. The fellow that brought it to me had paid 95 bucks at a rebuild shop. I could get a spark at the points one time out of ten or so snaps of the impulse. First thing I checked. Put in a good armature and no change. Took and another case I had with good magnets and assembled it and had spark out the plug wires.
I took that magneto to the fellows place timed the engine and he said it ran better than it ever had. Probly had weak magnets for a long time.

 

[John T]

The ohm meter test will tell you if the points plate has a good ground to the rest of the case via those rear plate springy contactors PLUS it would show if the points spring is shorted to ground.... Put an ohm meter lead to case ground and the other lead to the points,,,,,0.5 to 0.7 ohms points open and near zero with closed tells the story about shorts and grounds.....Then insure the coils secondary is in the 5 to under 10 k ohms range and the impulse assembly winds n trips. You can only get about 1 turn of pre load spring wind which should yield a good loud sharp SNAP each 180 of rotation which is CCW facing the rear of mag looking at the impulse

LET ME KNOW WHAT YOU FIND

John T

 

[Anonymous-0]

A big thank you to everyone who took their time to help me. Checked what everyone told me to check and the problem was with the points.
They were grounded!!!!!!!!!
On the back of the point spring where it fastens (connects) with the primary coil wire on the block, there were 2 small nnalert of metal that were barely touching the the condensor bracket. After removing them, it is FINE. Hate to say how many hours I spent on it. I had never run into this before and without you guys help, I would probably have given up. Again, thanks to all who offered help. Hopefully others will read the advice offered and not have to go thru what I did. A simple fix, but not knowing where to look made a lot of work. This is one lesson I will never forget. Appreciate the ideas and would not have gotten it without the most appreciated advice. jim in ill

 

[John T]

CONGRATULATIONS........

Yep, grounding of the points at their spring is one of the things I mention at my Seminars thanks to my friends Duane and Glen PLUS my own experience........Shorts or a poor ground caused by the other rear tabs not mating can both be verified by the simple ohm meter on the points test with them open and closed......

Best wishes and thanks for the feedback

John T

 

[greenmech]

Thanks for the feedback, and good luck with your tractor. Ron Mn.

 

[Brian Jasper co. Ia]

Dick, have you ever tried to recharge a magnet? I was told once it can be done with a toy train transformer, and it works. I have recharged the magnets in various Wico and FM mags with a 12V power supply and a coil of solid copper wire carefully wrapped around the magnet. Only takes a couple seconds of on time to put the magnetism back in.