Intermittent spark from magneto

[13fx]

This W4 is the first magneto tractor I've ever had. I figured since I'm waiting on carb parts I may as well see where the timing was on it and didn't seem to get any spark at all. I had moved the timing light to the coil wire and found that it would spark once every 3-6 times the drive would trip. Not really sure where to go from here, also I don't see a condenser anywhere is there supposed to be one?

 

[old]

This W4 is the first magneto tractor I've ever had. I figured since I'm waiting on carb parts I may as well see where the timing was on it and didn't seem to get any spark at all. I had moved the timing light to the coil wire and found that it would spark once every 3-6 times the drive would trip. Not really sure where to go from here, also I don't see a condenser anywhere is there supposed to be one?

Most common problem with lack of spark is the points need to be cleaned and or replaced

 

[13fx]

Points looked good, but drug the file over them anyway. The gap is .014 so I feel good about that. As I'm putting the cover plate back on I see two small indents to the right of the groove for the rotor. The first has an R and the second is L. There is also a grove coming from both of them. Looks like a set of timing marks what's the purpose?

 

[wore out]

This W4 is the first magneto tractor I've ever had. I figured since I'm waiting on carb parts I may as well see where the timing was on it and didn't seem to get any spark at all. I had moved the timing light to the coil wire and found that it would spark once every 3-6 times the drive would trip. Not really sure where to go from here, also I don't see a condenser anywhere is there supposed to be one?

The condenser is inside the magneto, beneath the coil, mounted crosswise.

As the other guy said, the breaker points are the most likely cause of intermittent spark.

Below is a link to the Official Blue Ribbon IH Magneto Manual, you have an H4 magneto.

https://farmallcub.com/rudi_cub/www...Magnetos/GSS-5035 Service Manual Magnetos.htm

Probably NOT directly related to your original question, but check the rotor timing as shown in the manual.

 

[wore out]

Points looked good, but drug the file over them anyway. The gap is .014 so I feel good about that. As I'm putting the cover plate back on I see two small indents to the right of the groove for the rotor. The first has an R and the second is L. There is also a grove coming from both of them. Looks like a set of timing marks what's the purpose?

The "R" and "L" markings correspond to a marking (beveled tooth) on the little drive pinion cleverly hidden under the cover with two screws.

As I mentioned in my first reply the Blue Ribbon Manual will give the details on verifying that the rotor is timed correctly.

 

[13fx]

Thanks for the link. So far dragging the points with a file did nothing. I decided to change out the shutoff wire real quick since it looked terrible and that seems to get the timing light to flash a little more but still not every time. I'll be digging through that link for a while.

 

[wore out]

Thanks for the link. So far dragging the points with a file did nothing. I decided to change out the shutoff wire real quick since it looked terrible and that seems to get the timing light to flash a little more but still not every time. I'll be digging through that link for a while.

Disconnect the "shutoff wire" completely for now to rule out the wiring and the "kill switch" completely.

Also, does the impulse "latch and trip" without fail, each time?

If NOT, you need to look at checking the impulse for wear and be sure that it's not gummed up and operates freely.

 

[Janicholson]

Points looked good, but drug the file over them anyway. The gap is .014 so I feel good about that. As I'm putting the cover plate back on I see two small indents to the right of the groove for the rotor. The first has an R and the second is L. There is also a grove coming from both of them. Looks like a set of timing marks what's the purpose?

R and L is for RIght hand or left hand rotation CW or CCW. for assuring the rotor is positioned for the impulse to work in that direction. Jim

 

[13fx]

Disconnect the "shutoff wire" completely for now to rule out the wiring and the "kill switch" completely.

Also, does the impulse "latch and trip" without fail, each time?

If NOT, you need to look at checking the impulse for wear and be sure that it's not gummed up and operates freely d

Ive disconnected the wire now and, it sounds like it trips twice on every full rotation without fail. After working on this a bit more I seem to have it sparking most of the time, but two of the cylinders are intermittent now. I'm going to order a new distributor cap and see if that cleans up the rest. I'm feeling fairly confident that the problem doesn't reside with the magneto anymore and more to do now with old worn cap and plug wires. Thanks everyone for walking me through my first magneto. And double thanks wore out for the manual.

 

[wore out]

Ive disconnected the wire now and, it sounds like it trips twice on every full rotation without fail. After working on this a bit more I seem to have it sparking most of the time, but two of the cylinders are intermittent now. I'm going to order a new distributor cap and see if that cleans up the rest. I'm feeling fairly confident that the problem doesn't reside with the magneto anymore and more to do now with old worn cap and plug wires. Thanks everyone for walking me through my first magneto. And double thanks wore out for the manual.

Did you verify that the rotor timing is correct?

 

[13fx]

Did you verify that the rotor timing is correct?

Not yet, just wore my backside out turning that hand crank. #1 on the dist cap is the only one that won't fire yet, and it won't do it at all. I'm going to verify the timing after dinner, maybe. Even though that is a distillate motor with lower compression it's had me huffing and puffing more than the wolf.

 

[rustred]

Points looked good, but drug the file over them anyway. The gap is .014 so I feel good about that. As I'm putting the cover plate back on I see two small indents to the right of the groove for the rotor. The first has an R and the second is L. There is also a grove coming from both of them. Looks like a set of timing marks what's the purpose?

the purpose is, R is for clockwise rotation, and L is for counterclockwise rotation. and yes they are timed. the little gear has a timing mark to line up to the R as yours is right hand rotation as all the gas models except the w9 which is Left hand rotation due to the idler gear in the timing cover , the diesels are all Left hand rotation.

 

[13fx]

Did you verify that the rotor timing is correct?

When I checked, the timing was around 7.-10. past TDC. I now have it timed for TDC as per the manual. Now the manual says to set it at TDC, but I was under the impression that the impulse was supposed to trip at 5. From TDC which is the next mark, am I wrong on that or maybe I read the manual wrong?

 

[rustred]

No, the impulse needs to trip right at TDC . If it’s tripping before it will kick you if you use a hand crank.

 

[Hendrik]

Not yet, just wore my backside out turning that hand crank. #1 on the dist cap is the only one that won't fire yet, and it won't do it at all. I'm going to verify the timing after dinner, maybe. Even though that is a distillate motor with lower compression it's had me huffing and puffing more than the wolf.

Pulling the spark plugs significantly reduces the effort of hand cranking.

 

[teddy52food]

Ive disconnected the wire now and, it sounds like it trips twice on every full rotation without fail. After working on this a bit more I seem to have it sparking most of the time, but two of the cylinders are intermittent now. I'm going to order a new distributor cap and see if that cleans up the rest. I'm feeling fairly confident that the problem doesn't reside with the magneto anymore and more to do now with old worn cap and plug wires. Thanks everyone for walking me through my first magneto. And double thanks wore out for the manual.

If you need help on the mag, I do them as a hobby. I have the testers that takes the guess work out of it. Also have a magnet charger that gets the magnet up to snuff for a good hot spark.

 

[13fx]

Pulling the spark plugs significantly reduces the effort of hand cranking.

Sure does, but than I would have most likely stumped myself as to why I couldn't get spark at all and would have unnecessarily torn the entire magneto apart a couple of times before realizing that I had no ground for the wires. But now you did just give me an idea to check for that last stubborn no firing cylinder, pull, clean, and inspect the plug to make that it can ground from the electrode to the plug body into the block.

 

[Janicholson]

Sure does, but than I would have most likely stumped myself as to why I couldn't get spark at all and would have unnecessarily torn the entire magneto apart a couple of times before realizing that I had no ground for the wires. But now you did just give me an idea to check for that last stubborn no firing cylinder, pull, clean, and inspect the plug to make that it can ground from the electrode to the plug body into the block.

The removed plugs can be grounded on block metal, or a bare wire can be wrapped around each of the threads then put under a screw/bolt to assure a ground. The wires can be grounded without plugs in them as well. The spark will happen, ground or no ground. Jim

 

[rustred]

Sure does, but than I would have most likely stumped myself as to why I couldn't get spark at all and would have unnecessarily torn the entire magneto apart a couple of times before realizing that I had no ground for the wires. But now you did just give me an idea to check for that last stubborn no firing cylinder, pull, clean, and inspect the plug to make that it can ground from the electrode to the plug body into the block.

and here i thought you had the plugs out when you were checking for spark. i like them out and do the spark test watching how the plug fires. you can have a bad plug also. try another plug. you can watch the spark follow the firing order 1 3 4 2 with each click of the mag. you can also check your TDC timing that way also on number 1 cyl. by using a screwdriver or what ever is handy in your left hand to feel the piston come to tdc and the mag click at the same time while barely lifting the crank with your right hand. then double check it to the tdc timing mark , and it should be spot on. plug gap is .025. mag is .013. was just thinking a person could make a plug tester board out of 1/8 flat metal and drill and tap the holes for the plugs screw them in and ground the iron to the tractor with vise grips or a clip wire and then see the sparkies easily. i also check the spark with the tractor running also by pulling one wire at a time off and see if its nice and blue and snapping and jumps a 1/2 inch gap to the plug.

 

[13fx]

and here i thought you had the plugs out when you were checking for spark. i like them out and do the spark test watching how the plug fires. you can have a bad plug also. try another plug. you can watch the spark follow the firing order 1 3 4 2 with each click of the mag. you can also check your TDC timing that way also on number 1 cyl. by using a screwdriver or what ever is handy in your left hand to feel the piston come to tdc and the mag click at the same time while barely lifting the crank with your right hand. then double check it to the tdc timing mark , and it should be spot on. plug gap is .025. mag is .013. was just thinking a person could make a plug tester board out of 1/8 flat metal and drill and tap the holes for the plugs screw them in and ground the iron to the tractor with vise grips or a clip wire and then see the sparkies easily. i also check the spark with the tractor running also by pulling one wire at a time off and see if its nice and blue and snapping and jumps a 1/2 inch gap to the plug.

The removed plugs can be grounded on block metal, or a bare wire can be wrapped around each of the threads then put under a screw/bolt to assure a ground. The wires can be grounded without plugs in them as well. The spark will happen, ground or no ground. Jim

I wasn't planning on spending half of a day rotating a motor I honestly thought it was going to be as simple as cleaning the point gap so I wasn't going to go through all of that hassle of grounding the wires. But I am going to disagree on the spark still happening if it isn't grounded. If you pull a plug wire off of an engine and let it dangle in the air with the timing light hook to it you will not get any reading off of that light because nothing's happening there is no flow of electricity. It would be like having a condenser and just letting that dangle in the air instead of grounding it to the block.