Converting a cub lowboy from points to electronic ignition

[jaxcub2022]

Help! lol I have a cub lowboy that I have not been able to start after I messed with the distributior positioning. I fiddled with it to try annd resolve what i think was low compression last time I was mowing with it. I have had the cub over 20 years and it ran fine. But now when I try to start it it either backfires or just grinds on the starter. I had to have trhe starter rebuilt and I am now ready to go back in and try starting it again. I did get another set of points and after replacing the kit no joy. I see these electronic start kits that say "never have to do points again... the current kit I am looking at is a Electronic Ignition Conversion Kit, 12 volt negative ground 4 Cyl Delco distributor with clips. My cub was converted to 12 volt many years ago. I have a new battery and ready to try starting the cub again, should I buy the kit and get away from the points all together?? Has anyone had success with the electronic start kits? please advise.

[Glen]

Hi,
Since it is a LoBoy, I suppose it has a Battery Ignition unit. You didn't say.
I don't think a kit for a Delco distributor will fit an IH distributor. You would have to buy one for an IH distributor, for the Cub LoBoy.

I would give the engine a compression test, then you will know what it has.

I would use the points, and try to get it to run with the points first.
If it has a Battery Ignition unit, when the number 1 cylinder's piston is at TDC, the rotor should be pointing to the upper right post on the distributor cap, if the distributor, and spark plug wires, are still positioned the original way.
When getting it to run the 1st time when putting it together, usually they start easily if the rotor is pointing to the upper right, even if the timing is not exactly right.

Below are pages showing the Battery Ignition unit, and the points, and setting the gap.
Notice on the 2nd page, the distributor is originally turned so the small post on the side of the distributor is facing to the right, then the number 1 spark plug wire post is at the upper right.
The firing order is 1 3 4 2, going clockwise around the cap, looking ahead from behind the cap.
Be sure the wires are in the right posts on the distributor cap.

http://farmallcub.com/rudi_cub/www.clea ... age-11.jpg

http://farmallcub.com/rudi_cub/www.clea ... age-12.jpg

After getting it to run, the Cub service manual says to set the timing using a timing light, like cars with a distributor in the past used.
Below is a page from the Cub service manual showing the timing marks a Cub LoBoy should have, except for maybe the 1st LoBoys, they might have only mark number 1.
Mark number 1 should be aligned with the pointer when the engine is running at slow idle speed, 500 RPM.
Use only the pic and the words under it, they are talking about other things on the page.

http://www.farmallcub.info/manuals/gss- ... 001-43.jpg

Below is info for doing a compression test, if you need it.

Usually they say on here to give the engine a compression test, so you partly know what condition the engine is in.
Remove all 4 spark plugs so they are out of the engine at the same time.
Clean any dirt from around the spark plug bases before removing the spark plugs, so dirt doesn't go into the cylinders.
Use the starter for the test, not the hand crank.
Charge the battery fully before doing the test.
Charge a new battery too, they are not always fully charged. Use a small output battery charger, and let it charge slowly, it may take several hours.
Open the throttle fully, so the engine can get air for the test.
I write down the results so I have a record.

The Cub service manual says a Cub engine has 120 lbs of compression. That is probably for a new engine. Some less is ok, 90 lbs or more is ok.

[Clemsonfor]

If you can't get it to run as is I don't think an electronic ignition will solve your problem.

[Barnyard]

If you can't get it to run as is I don't think an electronic ignition will solve your problem.

[NJ Farmer]

It a pretty simple ignition system….maybe sit down with a hot cup of coffee and watch a few videos and read the ignition section of the maintenance manual and figure this out step by step.
I think throwing money at the problem won’t solve the problem, but a little studying and patience will prevail. These systems on the Cubs are strong and very reliable just slow down and read/watch how to set up the Cub ignition system. When it’s back up an running you will be proud of yourself for tackling this problem.
Regards,
NJ Farmer
If you think this ignition system is complicated look up a Pratt and Whitney R-4360 engine….that’s complicated!!!!

[Eugene]

Don't purchase an electronic ignition system. Much less expensive to use the standard points sytem.

Need to solve the possible low compression problem first and then get the engine running.

Back firing, usually ignition timing problem. Plug wires on wrong plugs?

[jaxcub2022]

This is all great advice, I appreciate the feedback, from the technical to the "hot cup of coffee and watch a few videos and read the ignition section of the maintenance manual and figure this out step by step."

Okay, regrouping my thoughts now. Brakes on buying the electronic ignition system.

Saturday I took my cub over to Zachary who was advertising an old tractor and he said he could get the points and timing set and get it running. My battery was old and did not hold a charge so I bought a new one to have a good battery to work with. I will share this information with him.

I use to be able to call dad and walk through these tractor issues, but he passed 7 years ago and I lost that support.

I will take this advice and any other advice anyone has to help on getting this tractor running again.

[jaxcub2022]

Hi,
Since it is a LoBoy, I suppose it has a Battery Ignition unit. You didn't say.
I don't think a kit for a Delco distributor will fit an IH distributor. You would have to buy one for an IH distributor, for the Cub LoBoy.

I would give the engine a compression test, then you will know what it has.

I would use the points, and try to get it to run with the points first.
If it has a Battery Ignition unit, when the number 1 cylinder's piston is at TDC, the rotor should be pointing to the upper right post on the distributor cap, if the distributor, and spark plug wires, are still positioned the original way.
When getting it to run the 1st time when putting it together, usually they start easily if the rotor is pointing to the upper right, even if the timing is not exactly right.

Below are pages showing the Battery Ignition unit, and the points, and setting the gap.
Notice on the 2nd page, the distributor is originally turned so the small post on the side of the distributor is facing to the right, then the number 1 spark plug wire post is at the upper right.
The firing order is 1 3 4 2, going clockwise around the cap, looking ahead from behind the cap.
Be sure the wires are in the right posts on the distributor cap.

http://farmallcub.com/rudi_cub/www.clea ... age-11.jpg

http://farmallcub.com/rudi_cub/www.clea ... age-12.jpg

After getting it to run, the Cub service manual says to set the timing using a timing light, like cars with a distributor in the past used.
Below is a page from the Cub service manual showing the timing marks a Cub LoBoy should have, except for maybe the 1st LoBoys, they might have only mark number 1.
Mark number 1 should be aligned with the pointer when the engine is running at slow idle speed, 500 RPM.
Use only the pic and the words under it, they are talking about other things on the page.

http://www.farmallcub.info/manuals/gss- ... 001-43.jpg

Below is info for doing a compression test, if you need it.

Usually they say on here to give the engine a compression test, so you partly know what condition the engine is in.
Remove all 4 spark plugs so they are out of the engine at the same time.
Clean any dirt from around the spark plug bases before removing the spark plugs, so dirt doesn't go into the cylinders.
Use the starter for the test, not the hand crank.
Charge the battery fully before doing the test.
Charge a new battery too, they are not always fully charged. Use a small output battery charger, and let it charge slowly, it may take several hours.
Open the throttle fully, so the engine can get air for the test.
I write down the results so I have a record.

The Cub service manual says a Cub engine has 120 lbs of compression. That is probably for a new engine. Some less is ok, 90 lbs or more is ok.

[jaxcub2022]

I put that picture of the plugs and wires on the distributor and marked the distributor cap with small scratch on the cap for 1,2,3,4, I had the wires marked where they were on the plugs counting 1-4 from fan back towards the center of the tractor. The firing order is 1 3 4 2 from the cast mold reading on the tractor motor. So is that clockwise around the distributor 1 plug, then 3 plug, then 4 plug then 2? to have the wire plug correct?

[jaxcub2022]

here is a picture of the firing order on the cub. Just wanting to make sure I get the wires on correct.. that is probably the reason for the backfires huh,....?

[NJ Farmer]

Get rid of the ballast resistor running off the coil. Wire it up exactly as the wiring diagram in the maintenance manual. I can’t stand when people try to re-invent the wheel. Back in 1940’s engineer spent many a sleepless night fine tuning this Cub into a work of art and someone along the line thought he can make it better.

Stay with the original wiring setup….anything added on is now “experimental” and has room for errors. Also makes it harder for us to figure out what is wrong!

[NJ Farmer]

Also make sure you put some threat sealant (pipe dope) on that bolt you removed and retorque all bolt IN SEQUENCE as per the maintenance manual…..VERY IMPORTANT TO TORQUE IN PROPER SEQUENCE!

Also you ignition system problems are most likely timing but make sure plugs are clean (or start with new plugs if unsure of condition….you may have a bad or weak plug) Also check point gap and dress the points with a file (or replace points if your unable to dress with file) if you replace the point always replace the condenser as well. They go together and a bad condenser will burn out you new points…

Finally if you cap and rotor look bad I would replace it as well…..bad gap in the cap equals bad firing.

I would like to also state that you have solid core spark plug wires or stainless steel braided wound core plug wires. Anything else is going to fail prematurely.
NJ Farmer

Y

[Glen]

My cub was converted to 12 volt many years ago. I have a new battery and ready to try starting the cub again,

Hi,
If the LoBoy is still 12 volts, you need to use the resistor near the coil. Don't throw it away if the LoBoy is still 12 volts. The LoBoy looks like it has an original IH 6 volt coil. They have to have a resistor to reduce 12 volts to 6 volts, or it will overheat and ruin the coil.

Yes, the firing order is 1 3 4 2, going clockwise around the distributor cap, looking ahead from behind the cap. I wrote that in my post above.
The engine cylinders are numbered 1 2 3 4, going from front to rear.

Thanks for the picture.
A pic from a little lower would be helpful, showing how the distributor cap and distributor are turned.
I don't know what the yellow thing is that looks like a cable, going diagonally across the left side of the pic. It looks like it touches the exhaust pipe. IH didn't put anything there like that is.
If it is electrical, the hot exhaust pipe will probably melt or burn the insulation off the cable, and it will short out on the pipe.
It's routing needs changing, especially if it is electrical.

Below is a page from the 1957 Cub LoBoy operator's manual showing the wiring routing.
The center pic on the page shows the battery cable routing for the cable from the battery to the starter, it goes on the right side of the tractor, and up in the 4 clips under the right side of the hood.

http://farmallcub.com/rudi_cub/www.clea ... e%2050.jpg

The page below shows what the numbers on the 1st page are, and has a pic with the hood off.

http://farmallcub.com/rudi_cub/www.clea ... e%2051.jpg

[Eugene]

Get rid of the ballast resistor running off the coil.

Original poster said the tractor has been converted to 12 volts.

The coil in the photos is very old, 6 volts, ballast resistor required.

[outdoors4evr]

My best guess... You replaced the points and new points usually come with a little bit of material on the points to keep them from rusting while they sit on the shelf. Gently clean the points (between the contacts). I wouldn't use sandpaper as these are new points, but maybe something less abrasive like a piece of paper or a points file (used sparingly).