400 no start, again

I think the problem is in the distributor. Here is what I have done and checked so far. New points, condenser , rotor and cap. With my test light, there is power to the resistor, bright light on one side, dim light on the other. Power to the coil. When cranking, I have a flashing light on the stud that goes thru the distributor wall, inside and out, power to the points, no fire past the points, no spark when the points open. The points are a 2 piece set, I dropped the brass screw that holds the striker to the distributor plate while changing the points. Looked all over in the grass and couldn't find it, finally took a screw out of the distributor on the JD 70 to get them installed, that screw is steel. The distributor is mounted sideways, so I put a dab of grease on the screw to hold it I place till I get it started in the hole. It seems to me that something is grounding the points inside the distributor, but I can't see what it is. The distributor shaft has end movement of about 1/4", there is some side play in the shaft. If the bushings were wore enough, would that cause no fire problems? Where can you get bushings for the shaft, IH dealer only or can you get them from Napa, etc? Is the steel screw instead of brass a problem? How does the fire get from the points to the rotor? Where to go next?? Sorry, if this is confusing, I'm so tired I can barely keep my eyes open. Thanks, Chris

that stud on the side of distributer is insulated where the coil wire goes. i would check that. its not the bushings or screw thats the problem ,dont matter how much bushing are worn it will still start.

I would agree with rustled on the stud and bushing that insulates that stud is worth giving a good look. Maybe bad wiring feeding the distributor?

That brass screw is not nessecary as I have steel screws in all of my distributors. It may help long term with corrosion but that would be it.

The wear in the shaft would not cause a no spark condition. It will cause erratic timing. It has to have a new bushing fitted and not a diy job without some machine work.

Play around with opening and closing the points with a screwdriver with the key on while you hold the big coil wire close to ground and see what you find. That is the first thing I do when I troubleshoot for spark.

If you are getting a flashing test light on the distributor side of the coil, the points are working as they should.

With everything you described, power to the coil, flashing test light... And there is no spark from the coil, just about has to be a bad coil.

The fire gets to the rotor from the coil wire when the points open. Pull coil wire from cap, hold wire end 1/4 inch from block, head, ground of choice, if you have a healthy spark it points to cap or rotor problem. The screw and a little slop in the dist. I don't think is keeping it from starting.

don't forget the dist needs to ground to the block
by using the test light it's not grounded to the dist I'll be you grounded to the block, frame or bat
clip it on the distributor and see if it still lights up
I've been caught trying to figure out a no spark with a non grounding dist
corrosion prevents a path for current flow
if you don't get the light lit up try running a temp ground wire from dist to block, frame or battery ground
good luck

You ask "How does the fire get from the points to the rotor"

IT DOESNT

The points only close/conduct,,,,,,,,,then open/disconnect the Low Voltage PRIMARY coil current. The HV is created out the HV secondary coil winding which comes out the top HV coil tower that connects to the rotor center that leads to the rotor tip.

With IGN on and a test lamp on the coils output to distributor terminal if it flashes full voltage on when the points are open then goes full OFF when closed they are doing their job.

You need to by pass the points condenser and distributor function to see if the coil is firing. Remove the coils LV primary output to dist terminal wire............place a jumper wire there on the coil instead,,,,,,,,,,Remove the coils HV output wire from the dist cap and place it instead to within 1/4 inch from tractor iron,,,,,,,,,,,,then with ign on each time you jump the small coil wire to ground then remove it THE COIL WIRE SHOULD FIRE TO GROUND..

If you work step by step through my procedure all this is explained in greater detail and will help find the cause of no fire BUT YOU HAVE TO WORK THROUGH IT


TROUBLESHOOTING A BATTERY POWERED EXTERNAL COIL TYPE IGNITION SYSTEM:
PRELIMINARY CHECKS:

(A) To see if it happens to be a cap n rotor problem and to see if at least the coil is firing, remove the coil wire from the distributor (leave coil end intact) and place its bare end to within 1/8 inch from tractor iron, turn her on n crank her over, and see if she jumps that gap with a good visible blue spark?????? If so but the plug wire ends (from wire end to 1/8 inch to frame) or the plugs themselves don?t fire, its a cap n rotor or plug wire problem. If the coil wire isnt even sparking, see below.

(B) Next open the cap and see that the points are gapped correct and indeed opening and closing as the engine is cranked and the distributor shaft rotates and MAKE SURE THEY ARE NOT BURNED OR PITTED OR CARBONED UP BADLY !!!!!!!!!!!! If so, running a point file between them to clean them up might make her run again HOWEVER that?s only a temporary cure, so if that cleaning makes her spark, INSTALL N GAP NEW POINTS. In the event they appear good but only gray oxide coated, non abrasively clean/buff/polish them using say a dollar bill or shop cloth etc. and see what happens.

MORE TROUBLESHOOTING IF ALL THE ABOVE STILL FAILS TO MAKE HER SPARK

1) THE VERY FIRST THING YOU GOTTA HAVE is voltage to be present on the coils high supply (NOT to distributor) terminal when you turn the Ignition switch ON. If not she cant ever fire, but in the event the ignition switch or circuit/wire down to the coil or any Ballast Resistor is bad or open, you can HOT WIRE it by jumping a hot ungrounded battery voltage source to the coils high input supply (NOT to distributor) side n see if she runs then???? If she fires hot wired, you could have a bad ignition switch ((That can happen, when Ignition is on, the switches IGN terminal must turn hot)),,,,,,,or an open Ballast (if it has one) or a bad/open wire from switch to coil.

If the switch is good, if you turn the ignition switch on and place a test lamp on the coils high (NOT to distributor) terminal SHE MUST LIGHT UP. If not again, look for an open Ballast Resistor (if it has one, it should read around 1.25 to 2 ohms across its terminals) or bad/open wires from the switches IGN output down to the Ballast (if it has one) and distributor.

2a) When the Ignition switch is turned on, voltage should appear on the coils high input side. That would be 6 volts on a straight 6 volt system or 12 volts on a 12 volt non external ballasted system, or around 6 volts on a 12 volt system that used a 6 volt coil plus an external Ballast Resistor and the coil is good and the points are closed and they and ALL wiring is good.

2b) To insure the coils low voltage primary winding is not bad/open, use an ohmmeter and measure its DC resistance between its lil + and -terminals. If its an open circuit (no continuity) its bad/open and will NOT work. It should measure around 1.25 to 2 ohms or so if its a 6 volt coil and maybe 2.5 to 3.5 if its a 12 volt internally ballasted coil. NOTE CAUTION have all leads and any voltage source DISCONNECTED FROM the coil for this simple primary winding continuity test. 3) Next, place your voltmeter or test lamp over on the coils other low to distributor terminal side, turn her on and crank the engine over.

4) A test lamp there should flash ON (when points are open) and OFF (when points are closed) as the engine is cranked slowly.

5a) If the lamp never comes on there, the coils primary is bad/open,,,,,,,,,,or the points are never opening,,,,,,,,,or theres a shorted/bad condensor (remove its lead to points and see if lamp comes on, if so, bad shorted condensor or its wiring),,,,,,,,or the points wire is shorted,,,,,,,,or the distributors side pass thru stud is grounded (use ohm meter to test that),,,,,,,,,or the points may have a shorted spring.

5b) If the lamp never goes off as engines cranked, the points are not closing or are bad,,,,,,,,or the wire or circuit is missing from the distributor to the points,,,,,or the distributors not well grounded to the tractor.

She cant fire the coil unless its low side is getting a conductive ground return path via closed points and then the circuit is open when the points open.

Be sure the condensor or its wiring is NOT shorted out and see if the lite comes on (when points open) with the condensor disconnected. If removing the condensor makes her spark, replace the condensor.

SUMMARY

Be sure the points are closing fully and open on high cam and ARE NOT BURNED OR PITTED OR CARBONED UP BADLY,,,,,,,theres voltage present on distributors high side at all times when ignitions on (or its a bad switch or open ballast or bad wiring to col),,,,,,,voltage on coils low side flashes on and off as distributor is cranked,,,,,,,,,condensors not bad/shorted,,,,,,,,no shorts in wires to points and no shorts in pass thru side out distributor stud,,,,,,,,coil has continuituy.

You may luck out n just need a new set of points. If the coil wire fires (see above) and the plug wire ends to 1/8 from frame but NOT the plugs, they are badddddddddddd. Check them BOTH.

Good Luck n God Bless, post back any questions and your findings and any questions.

John T Nordhoff in Indiana, retired electrical engineer who usually lurks over on the Mother Deere boards versus over here on the ?dark side?.
John Ts Testing

Bingo, easiest and quickest.

Ground for the points is inside the distributor where the fixed side of points screws to distributor base. If the test light is flashing the points are getting power and are switching and the distributor is grounded.

If the description is accurate, it points to an open in the coil secondary. Another possibility is on an old coil there can be extreme rust and corrosion at the inside of the large coil output causing lack of contact with the coil wire.

that's true but the dist still has to make a ground connection he block to complet? the circut

Correct. And, since the points are opening and closing and causing the test light at the side input to the distributor to flash, this confirms that the distributor is grounded to the tractor frame. Points ground through the distributor to complete their circuit. Test light is on when points are open and off when points are closed. An ungrounded distributor would be equal to open points and the light would not go out.

By hooking the test light to ground you are only proving the the power comes up the wire and back out the test light that's creating an alt path way to ground unless you actualy clip the ground wire directly to the dist
You can recreate the light working by totally removing it from the motor and hooking the power wire to the dist and using a test light on the points grounding the test light to the tractor
Electricity doesn't care how it gets back to ground just that it can
By hooking the test light up to the mounted distributor instead of connecting it to an alternate ground point is how to confirm the dist is grounding back to the battery
Remember the points mount to an advance plate thats mounted to the dist then the distributor is mounted to the motor for a grounding point as well as a mounting place and there is at least 3 points in that short chain of connections that can be corroded preventing an electric current making a complete circuit back to ground