JD 820 Pony issues

Ive managed to get diesel engine to run, starts very easily but does smoke a little but might improve with running. Im having issues with the pony motor, I fitted new coils, points, condensers and spark plugs and spark plug leads earlier but had carburation problems. I think carb is doing better now but Ive a spark problem. Looking at distributer there is spark from the bottom right and top left plug lead. Ive swapped the spark plugs just incase its a plug issue and its still the same leads that give spark. Top right and bottom left lead not producing anything. I checked that leads are properly located. An ideas on whats preventing diagonally opposite leads to behave this way?
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Bill, the spark system is peculiar. If you search on here you will find many threads which detail how the v4 pony gets its sparks. Are you sure the the plug leads make good contact in the coils? and the plugs are good?
When you have a diagonal issue, I think that you have both coils ok, and the points set properly, so I would be looking at the leads, and checking for good clean contact everywhere, you need good contact as you will find from the other threads.
Search for F I T and Cloonie posts, those guys seem to know the v4 pony inside out!
If you weren't so far away I would pop round and offer some help, but I'm in Northumberland...
 

It is a lost spark system that fires two plugs in series at once. There really is not a path through chassis as there is in a ordinary distributer system. Sparking a plug to chassis isn't going to work the same.
One failed wire or one failed plug can eliminate spark from two cylinders.
There are two types of internal connections inside the coil's high voltage side and two different types of spark wire leads. If the two styles are mixed the spark will be weak to non existent .
Autolite 437 non resistor plugs will eliminate open spark plug internals.
 
When you say bad cables or plugs will eliminate spark on two cylinders do you mean both from the same coil or could it be diagonally like Im describing?
 

The other perfectly good wire and plug won't fire on the same coil if there is a faulty wire or plug on the other side of the coil which will cause an open circuit.
Two plugs sparking or none, usually.
 
Make sure you have the correct match on the spark plug wires and the coils. The "original" design plug wires have a bayonet terminal on the end that snaps into internal springs in the coils. The aftermarket coils have barbed posts inside the coils and the plug wires have no end terminals and they "screw" onto the barbed posts in the center of the plug wire. Also, when testing for spark, both plugs on each side must be properly grounded when cranking the engine. Usually with good coils if one plug is firing the other plug will also fire if it's grounded.
 
This MAY help.

That distributor is actually two completely separate distributors in one frame. The front & rear basically have nothing to do with each other except that they share the same metal box, they share the magnetic pole piece, they share the cam that breaks the points & they share the power lead! Besides that they have nothing in common with each other!

The spark current in these goobers is in a loop that goes out one wire to the first plug's gap then across the gap to the plug's body then over to the body of the OTHER spark plug, across that gap and into the high voltage plug wire to get back to the coil! Front plugs work this way on the front coil. Back plugs work this way on the rear coil.

Seeing spark on opposite corners hints (to me) you have bad or wrong coils. I'm thinking your spark is going out one wire like it is supposed to but then once in the frame of the tractor it's finding some other path back to the coil winding!

A few tests may tell what's happening.

If all 4 plug wires are making good contact with the coil winding in the high voltage ports which others have correctly mentioned is necessary, you SHOULD see the secondary winding's resistance between top & bottom wires of the front coil and the same resistance between the top & bottom wires of the rear coil. These should definitely NOT be open! I don't have data in front of me to know what they SHOULD measure but I'd suspect 10 K or so. Maybe 20.

In these distributors, you should read infinity from all 4 plug wires to the frame! You should see infinity when checking top front to each rear. Bottom front to each rear also should read infinity. My guess is you won't find these readings and that the problem is either an assembly matter (actually kinda hard to do them wrong), or the wrong or bad coils!

If you see two plug wires measure high and two measure low to the frame, remove the coils from the distributor (leave 'em on the pole piece) and check the resistance between the low voltage wires and each PLUG WIRE of each coil. The low voltage wires and the high voltage wires should not electrically meet each other inside the coils. If they do, these are either the wrong coils or they're just plain bad.

I know I'm not telling you what is wrong here but I hope this helps you understand that WICO box a bit better!

I hope it helps!
 

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