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Antique Farm Tractors Vintage farm tractors on rubber tires with various implements. Ford, John Deere, Oliver, McCormick and more.

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Ford 4000 Gas Tractor, Electronic Ignition Conversion Weird Problem and Solution


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  #1  
Old 07-25-2014, 06:32:08 PM
Pete Spaco Pete Spaco is offline
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Default Ford 4000 Gas Tractor, Electronic Ignition Conversion Weird Problem and Solution

I bought a 1962 Ford 4000 Industrial with a backhoe and loader about 10 years ago from a friend. He had converted it to 12 volt negative ground electronic ignition, using a Genesee product. The ignition system has worked fine until 2 days ago.
All of a sudden, while grubbing out stumps, it started running on only one or two cylinders. I shut it down and cleaned the plugs, because it burns oil and that always fixes it.
Well, it didn't fix it this time. I wouldn't start, but it would fire on about one cylinder from time to time.
Troubleshooting, I found a weak spark only now and then, and not on all cylinders.

I opened up the distributor and couldn't find anything wrong at that point. Stymied, I went to town and got a new rotor and distributor cap. No help. (Shotgunning, I know. You won't tell anybody will you?)
Now I looked more closely at the distributor.
Removing the "dust cover":
-I saw that the Genesee "kit" looks pretty much like a Pertronics kit.
As I looked down at the "magnet wheel" area and saw a couple of interesting things:
-The plastic magnet wheel looked as though it had been rubbing on something and had actually extruded itself upward a little, leaving a thin layer of plastic about 1/8" higher than the part itself. I still am not sure what caused this.

-Secondly, I saw a tiny silver colored piece of metal just below the magnet wheel sitting on the distributor plate.
When I pulled out the magnet wheel, I saw that all 4 magnets were missing!!!!

Apparently, the magnets had been originally cast into the plastic magnet wheel. And, I assume that whatever made the plastic heat up and melt a little, caused it to let go of the magnets.
Anyway, I did find all four magnets. And I decided to epoxy them back into their recesses. I could see that each magnet had one slightly shiny side, so I assumed that would be the side to face inward. I confirmed that the shiny sides all had the same polarity with a compass. This seemed to confirm that I'd be able to get them all in there with the same polarity. They'd all either be right or they'd all be wrong.
I know that different Hall Effect sensors operate on different polarities, but I still don't know if this 25 year old Genesee kit used a Hall Effect sensor or some other reluctance-based magnetic pickup.
Anyway, I did epoxy the magnets in place and it worked great.

You can see my backhoe on my "Ugly Tractors" page at:
http://www.spaco.org/VehicleMaintena...lyTractors.htm

Pete Stanaitis
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  #2  
Old 07-26-2014, 02:50:32 AM
Thaumaturge Thaumaturge is offline
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Default Re: Ford 4000 gas tractor, electronic ignition conversion wierd problem and solution

Quote:
Originally Posted by Pete Spaco View Post
I know that different Hall Effect sensors operate on different polarities, but I still don't know if this 25 year old Genesee kit used a Hall Effect sensor or some other reluctance-based magnetic pickup.
Anyway, I did epoxy the magnets in place and it worked great.
While Hall Effect itself was first noted in 1879 by Edwin Herbert Hall, its use in small solid state sensors has mostly evolved in the past 15 years or so. Likely the Genesee kit uses just a trigger coil. As such it is probably a good thing you noted likely polarity on your magnets when you remounted them. Opposite polarity may not have even prevented firing,but likely would have affected exactly when the firing occured. The circuit is no doubt intended to fire on either rising or falling edge of the trigger pulse from the pickup. A reversed magnet would actually send a negative pulse to the CDI. If the input is capacitively coupled, you'd still get a positive pulse into trigger input, but it would be measurably delayed as the rising edge would occur on the end of trigger pulse, rather than on front edge.....

Probably more than anyone might care to know about the subject. Sufficient to know that polarity can make a difference.

As to your tractor, I'm envious, ugly or not. Beauty is in the eye of the beholder. Looks gorgeous to me, just based upon what I could do with one like it on my little 5 acre plot of land.

Doc
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Old 07-30-2014, 02:41:11 PM
Pete Spaco Pete Spaco is offline
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Default Re: Ford 4000 Gas Tractor, Electronic Ignition Conversion Weird Problem and Solution

More info on the cause of the magnets falling out:
I contacted Genesee and explained the problem. They said that sometimes, the mechanic looses the gasket between the "dust cover" and the distributor base causing the dust cover to sit lower on distributor. Then the magnet sleeve (I said "magnet wheel" in my previous post) may rub against the dust cover. The magnet sleeve heats up from the friction and may melt itself. That is just what happened to me.

He said they have heard of situations where the magnet sleeve actually "welds itself to the distributor cap"! They simply cut out the center section of the dust cover so that can not happen. He said the problem is more likely to happen if the distributor bearings are worn.

Pete Stanaitis
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