jerryinga

Member
I am working on a Wico C on a John Deere H. The tractor including the mag was rebuilt about five years ago. The tractor is only used for parades and shows and runs great but cranking which is hand start has become a big problem I have decided spark is the problem so I have replaced points condenser and rotor. I have read somewhere you should have a good blue spark, I am getting a spark but it isn't blue and will not pull but about a quarter inch. Everything is clean with new wires what is going wrong what do I need to do to get a good spark I am tired of pulling the tractor to crank especially when everyone is watching at a show. Please help. Thanks
 
It could one or a combination of several things.

It could be point gap. Point gap is more critical in a magneto than in an electric distributor!

It could be the secondary winding of the coil is not totally bad (because it does work) but it may no longer be totally good either! They can be good enough to run well but still too tired to start well. Once it's running, parts are turning faster & they work better. Sparking hard enough to start it is the toughest job there is for a mag! What you describe hints of a high resistance secondary winding.

The impulse spring could be weak causing the spark to also be weak.

It's not so likely to be the condenser. Those usually give more grief once running or warmed up. If it runs OK it's not so likely to be the condenser but it's not impossible.
 
Try filing and setting the points. I've found most of the time hard starting is point corrosion from sitting. Even if they look good they still hinder the spark. Worth a shot. Good Luck!
John
 
I have gone back through the mag and sanded all contact location including the points. That seemed to help, one last question, which way would improve the spark closing or opening the points?
Thanks
 
Jerry BTDT I find tractors are SHY when it comes to hand cranking. I used to have mine set up so they would start the VERY FIRST ROLL OVER OF THE FLYWHEEL time after time UNLESS PEOPLE WERE WATCHING in which case you couldn't start them with a stick of dynamite and the more people watching the harder they were to start ITS TRUE. I took a B to the State Fair that ALWAYS started the first or second roll over and it was on my trailer and a HUGE crowd gathered to watch me start it YOU GUESSED IT she refused to start despite my turning and sweating and maybe cursing lol. I walked away and everyone left and I walked back up on the trailer STARTED FIRST TURN !!!!!!!!!!!!

HERE ARE MY INITIAL THOUGHTS

1) Even with new points they can have a light oxidation or film or protectant so "lightly" clean buff polish them maybe with a dollar bill drug between them.
2) Gap is critical and while 0.015 is an approximation and the recommended gap, the edge gap method is best but takes some time and effort.
3) A weak impulse spring can cause a weak impulse spark, it needs to make a loud sharp SNAP versus a faint dull clink when it impulses but that's hard to quantify and describe over the net. Spring may be weak.
4) START IMPULSE TIMING IS CRITICAL it needs to snap right at TDC and if too late she's harder to start but if too fast the flywheel can kick back. I set mine as fast as I can up to TDC just BEFORE its too fast where she kicks back.
5) Sure a magnet can over a long time grow weaker and a recharge may help, but more often its the above that's the problem
6) Mine started best with the throttle set to slow idle AND DONT OVERCHOKE AND WET GAS FOUL THE PLUGS
7) Good fresh plugs help, I liked NON Resistor plugs and pure wire core plug wires when using a Mag ignition
8) Ive seen H's where the driver could sit on the seat and with his shoe turn the flywheel over and they started

You have a Wico C and ONLY asked about it so I'm NOT going into what mags are good or bad or other side issues

Points, plugs, timing, weak spring I suspect BEFORE a bad coil or condenser so try this and we can dig deeper as needed.

Sure there are other tips and I missed some, so maybe the other fine gents can add more

John T
 
Sanding can leave particles on points surfaces and/or remove too much critical shiny coating. I prefer less abrasive methods to clean/buff/polish, maybe a dollar bill and a points file versus any type of sandpaper. If so bad a file is needed its time to replace. They may have oxidation or a film that needs buffed off if new. Open or close as necessary to get 0.015. See my post above

John T
 
Could be many things, but I'd make sure the magnet inside is still okay. Especially if you've already checked the points, capacitor, impulse, and coil. If the magnet is weak, you are wasting your time unless you get it recharged. And yes, they DO get weak, contrary to what I've seen some people claim on these forums.

Points gap determines dwell-angle (how long they stay closed while the coil charges for spark). The optimum setting is a compromise and you should stick to the stock setting. To be technical, the narrower gap increases spark potential to a degree.
 
I am getting a spark but it isn't blue and will not pull but about a quarter inch.


Does this mean it will jump a quarter inch gap? If so, this is what you want. Of course it should be blue. Are you testing it with a bare wire out of the cap against metal that's clean and grounded?
 
Jerry, a bit more information regarding your specific question below "which way would improve the spark closing or opening the points?"

While the factory spec calls for a points gap of 0.015 THAT IS AN APPROXIMATION and what's commonly used and recommended (when all is new and perfect with no slop or wear its real close) the more accurate setting is so the points break open when the edge gap is 0.095. Somewhere I have my late expert friend Duane Larson's presentation on this subject at a Gathering of the Green Conference, but I would have to save and forward it as a PDF file. HOWEVER if you're close I doubt a very very slight change in your points gap (although sure it makes a difference) is the MAJOR cause of a weak spark. Instead Id suspect those causes I listed in my post below.

One other possibility I thought of (If I recall, its been a long time and I think its on the C Mag) is if the brass clippy that connects between the inner cap & coil contact button is corroded or loose or carboned. Seems like the X mag used a spring there while then C had a brass clip BUT NO WARRANTY IM RUNNIN ON OLDDDDDDDD MEMORY CELLS HERE LOL

John T
 
Here is some info from my 1959 Deere dealer's manual. Note that spark test is supposed be jumping a .35" gap (over a 1/4 inch) at 1000 RPM. Main adjustment I have not seen mentioned here is the edge-gap of the magnet/rotor in respect to when the points open.

Also some info on recharging the magnet. I have a charger here I have used many times.
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Yo JDEM, you stated "Main adjustment I have not seen mentioned here is the edge-gap of the magnet/rotor in respect to when the points open."

You must have missed it, (Hey I've often missed something trying to read through each and every post grrrrrrrrr lol) FYI and others, here's what I indeed mentioned right down there below:

"While the factory spec calls for a points gap of 0.015 THAT IS AN APPROXIMATION and what's commonly used and recommended (when all is new and perfect with no slop or wear its real close) the more accurate setting is so the points break open when the edge gap is 0.095."

My experience was once the precise edge gap method of adjusting the points was completed, you then check the points gap using a feeler gauge and as long as its still at least 0.013 (best I recall, may have been slight different I apologize) leave well enough alone, HOWEVER, if the gap is much less then there's excess rubbing bar wear and its time for a new set of points. The reason for using the edge gap method of adjusting points is that's the place the coils LV primary current is the greatest AS I RECALL NO WARRANTY MIND YOU but I believe that's correct

Hope this helps

Take care, best wishes and may God Bless you

John T
 
Thanks to everyone who posted I think I have it about ready to put back on the tractor
Get it all timed up and see if it works
Thanks again
 

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