Allis will not start

FtInn Farmer · Nov 27, 2019

I have an Allis Chalmers CA and am having some starting issues. The tractor was running fine; now it will not start. I have checked the magneto and it is firing. However, when I check the spark at the plug; it will fire once or twice and quit. It appears to be the same on all the plug wires. I checked the continuity of the wires and they reading 1.94 - 2.24. Could the problem be in the wires, at the output of the magneto, or the rotor button and/or cap? The plug wires are old; they have a wire center. Any ideas?

Steve@Advance · Nov 27, 2019

Intermittent fire, I would go through the motions of setting and cleaning the points, just to say I did. Then establish a reliable 1/4" spark from the coil each time the impulse spring releases.

Clean and dry the rotor and cap, inspect them carefully for carbon tracks, cracks, check the contact button connection for the rotor to cap.

The wires should be good as long as they are not touching each other or any thing.

greenmech · Nov 27, 2019

Replace points and condenser. Ron MN

Bob Harvey · Nov 27, 2019

CRC 'Lectramotive'(sp) spray is a good tool.

Northvale PA · Nov 27, 2019

My dad?s TO-20 was running rough, then not at all. I replaced the coil, started but then quit. Eventually I
filed the points and it ran like a champ. Go for the points, yes.

Bob · Nov 28, 2019

(quoted from post at 19:41:26 11/27/19) I have an Allis Chalmers CA and am having some starting issues. The tractor was running fine; now it will not start. I have checked the magneto and it is firing. However, when I check the spark at the plug; it will fire once or twice and quit. It appears to be the same on all the plug wires. I checked the continuity of the wires and they reading 1.94 - 2.24. Could the problem be in the wires, at the output of the magneto, or the rotor button and/or cap? The plug wires are old; they have a wire center. Any ideas?

Replace the breaker points, filing them is only a "band aide" fix.

There's exceptions to every rule, but based on what you posted breaker points not consistently making good contact would be way out in the lead as the prime suspect for causing your intermittent spark.

Wires, cap, coil, condenser, rotor, etc. can all fail, for sure, but generally either work, or they don't.

John T · Nov 28, 2019

I would start by replacing and correctly gapping the points. Condensors can fail but I suspect the points first followed by condenser if needed. Wires cap n rotor would follow if needed.

John T

Dave BN · Nov 28, 2019

Do you hear the impulse click each time a plug should fire? Also check
the rotor closely. I had one with a loose, wobbly contact that drove my
crazy. Looked ok but would move out of place with the pressure of the
cap installed.
Happy Thanksgiving.

Dave

TomA in CA · Nov 28, 2019

Take points out and visually inspect. Reface with dremmel. New
points are of inferior quality.

Brent Zappe · Nov 28, 2019

these are things in the past I have found wrong with a Magneto Fairbanks type. 1 gasket has to be the thick one not thin. Because it needs clearance or the rotor nylon wheel will hang up. Than the nylon wheel that rides the gear gets striped. 2. Check and make Shure the rotor inside of big cap moves around on this nylon rotor as the engine cranks. 3. get a spark tester hook up to the spark plug wires crank the engine around looking at the spark tester to see if you have spar on that cylinder. The problem is the nylon rotor gear on the big black cap will some times strip a tooth and cause it to not turn but stick in one position. Just some thing to think about good luck. Referring to Hot to restore Tractor Magnetos by Neil Yerigan.page 89-94 in the book.

4wdtom · Nov 28, 2019

If the ideas you have received don't help it may be a more serious magneto problem. I was having starting problems with my AC WD this summer. It would run fine once
running but would not start. Finally thought the spark was intermittent and took the magneto to the shop that does them around here. He cleaned the points, adjusted
them, tried a condenser and different cap and rotor, no improvement so I left it for further work. Turned out the magnet would not hold it's magnetism. He installed a
NOS magnet and it has been like new. Said it is rare for the magnet to fail in a FM magneto. For those lucky enough to be near this shop it is Mark's Magneto in
Colchester CT. Highly recommended by those in this area.

JMS/.MN · Nov 30, 2019

A Model CA should have a distributor, not a magneto system. Which one is it?

Jim.ME · Nov 30, 2019

Magnetos were original equipment on some CAs, primarily the earlier ones I believe, not all had distributors.

FtInn Farmer · Dec 8, 2019

(quoted from post at 17:41:26 11/27/19) I have an Allis Chalmers CA and am having some starting issues. The tractor was running fine; now it will not start. I have checked the magneto and it is firing. However, when I check the spark at the plug; it will fire once or twice and quit. It appears to be the same on all the plug wires. I checked the continuity of the wires and they reading 1.94 - 2.24. Could the problem be in the wires, at the output of the magneto, or the rotor button and/or cap? The plug wires are old; they have a wire center. Any ideas?

This is a follow-up to the above issues with the magneto. The mag is a FM-J4B, I am getting fire out of holes 2 and 3 of the distributor cap but nothing out of holes 1 and 4, I can not see a crack in the cap anywhere. I have cleaned the holes and the pins are good. Any more ideas?

Allis will not start

FtInn Farmer

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Steve@Advance

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greenmech

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Bob Harvey

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Northvale PA

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Bob

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John T

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Dave BN

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TomA in CA

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Brent Zappe

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4wdtom

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JMS/.MN

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Jim.ME

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FtInn Farmer

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