Farmall cub timing

A valve is your issue probably a bit tight not letting it fire with compression. A compression test on that cylinder would tell you if they are so tight they leak.
Cat guy, read all the replies, reply 3 the OP says it has a 100# compression in cylinder 3. That should be enough to make it pickup when the spark is returned to that cylinder. And reply 16 says he reset the valves. Not sure why a guy would look at a thread at all if he doesn’t have time to read all the replies?
OP, a head gasket would have to make an obvious ppsss, ppsss sound on every compression stroke to leak enough not to fire. If it was pushing that much compression in the radiator it would be shoving water out the cap. Wherever you think the pressure is going as I said above with a 100 psi the spark cutout to that cylinder would/should not be noticeable.
 
Cat guy, read all the replies, reply 3 the OP says it has a 100# compression in cylinder 3. That should be enough to make it pickup when the spark is returned to that cylinder. And reply 16 says he reset the valves. Not sure why a guy would look at a thread at all if he doesn’t have time to read all the replies?
OP, a head gasket would have to make an obvious ppsss, ppsss sound on every compression stroke to leak enough not to fire. If it was pushing that much compression in the radiator it would be shoving water out the cap. Wherever you think the pressure is going as I said above with a 100 psi the spark cutout to that cylinder would/should not be noticeable.
Thanks, I had to take a break, but back at it now. Not head gasket, no psss ppsss or bubbles in water. Drove the Cub around under load and high speed low speed back to the shop. Pulled the plugs and number 4 looks a lot different than 1,2, and 3. Plugs are pictured from right to left with #1 on the right. What's up with that? Plug gap at .023.
Joe
 

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Problem still persists, had to set it aside for a while, but the more I look at it I may have installed the mag/gov gear in wrong????
I know it may sound stupid but what else??? I think I aligned the governor gear with it's 2 marks with the cam gear 1 mark. Won't know until I pull it apart.
 
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Problem still persists, had to set it aside for a while, but the more I look at it I may have installed the mag/gov gear in wrong????
I know it may sound stupid but what else??? I think I aligned the governor gear with it's 2 marks with the cam gear 1 mark. Won't know until I pull it apart.
If the governor was removed it has to be timed. Unfortunately the timing marks are on the back of the gear( in the engine) they can only be seen by removing the magneto and the oil seal between mag and governor. BUT......it sounds like you are running and driving. Just one plug not firing? Try a different plug,heck try a 6 different plugs and wires......I seriously doubt it's a timing issue with the magneto or governor if it runs and drives
 
If the governor was removed it has to be timed. Unfortunately the timing marks are on the back of the gear( in the engine) they can only be seen by removing the magneto and the oil seal between mag and governor. BUT......it sounds like you are running and driving. Just one plug not firing? Try a different plug,heck try a 6 different plugs and wires......I seriously doubt it's a timing issue with the magneto or governor if it runs and drives
Ok all you guys are saying it's unlikely a timing issue so back to the plugs and wires. Did you see the video I posted above? You can see the spark and I did swap plugs around many times. Also, the mag worked fine on the smoking engine and not missing. Now I'm not sure how I aligned the governor, but I do remember taking caution to get it right I thought at the time.
Thanks for the input,
 
Ok all you guys are saying it's unlikely a timing issue so back to the plugs and wires. Did you see the video I posted above? You can see the spark and I did swap plugs around many times. Also, the mag worked fine on the smoking engine and not missing. Now I'm not sure how I aligned the governor, but I do remember taking caution to get it right I thought at the time.
Thanks for the input,
Timing does not cause a dead cylinder. Do u have wire core plug wires or carbon core. Just by looking at the plug boots it appears to be carbon core automotive wires. No good. That is a very weak spark. If the plug is good as you say follow the wire back to the cap and check the terminal inside.
 
Timing does not cause a dead cylinder. Do u have wire core plug wires or carbon core. Just by looking at the plug boots it appears to be carbon core automotive wires. No good. That is a very weak spark. If the plug is good as you say follow the wire back to the cap and check the terminal inside.
Ok don't know what wires or where they came from. Just ordered Wires, Rotor, and Distributor Cap. Plugs were new and rotated around the horn.
Thanks, update when order is received.
 
Ok got new distributer cap, wires, and rotor from Stiener Tractor. Installed cap and wires, no change, still missing on #3. Gerr. So now I decided to install the rotor because on the first attempt the rotor didn't just pull off. Removed the 2 screws that held the rotor in and out it came, gear toothed rotor, crippled up gasket and all. Bad decision, because now not only wrong rotor, but I did not notice which direction it came off. All the rotors that I have seen only went on one way. WT...... I have a mag manual somewhere; guess I'll have to read it now??
 
Ok got new distributer cap, wires, and rotor from Stiener Tractor. Installed cap and wires, no change, still missing on #3. Gerr. So now I decided to install the rotor because on the first attempt the rotor didn't just pull off. Removed the 2 screws that held the rotor in and out it came, gear toothed rotor, crippled up gasket and all. Bad decision, because now not only wrong rotor, but I did not notice which direction it came off. All the rotors that I have seen only went on one way. WT...... I have a mag manual somewhere; guess I'll have to read it now??
That is a good idea. The rotor is timed to the drive gear and has timing marks on the teeth. be careful with that issue. It is not obvious how to get a mag to trip when starting at TDC. because it runs at full advance. Read well. Jim
 
That is a good idea. The rotor is timed to the drive gear and has timing marks on the teeth. be careful with that issue. It is not obvious how to get a mag to trip when starting at TDC. because it runs at full advance. Read well. Jim
Thanks, I found my Mag service manual, but it does not cover a J4 mag. Just F-4, F-6, E4a, H4, H1, H, AH, EK, AP, Dixie, and Aero Mags. Are any of these close enough to be able to put the rotor back on?
 
Thanks, I found my Mag service manual, but it does not cover a J4 mag. Just F-4, F-6, E4a, H4, H1, H, AH, EK, AP, Dixie, and Aero Mags. Are any of these close enough to be able to put the rotor back on?
H4 would do it. A lot of FM mags have the tooth marks gone. I get the points at the point they are ready to berak then put the rotor so it lines up with a cap terminal & install it. Works every time!
 
Ok got it running again by setting top dead center without mag clicking for #1. Had a 50/50 chance of getting it right. My first chance was wrong and of course second chance worked perfect. Ok back to normal runs strong, but still missing on #3 cylinder. Did all the above and now I give up. Make me an offer. I'm in Granite Bay, California 95746.
 

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Take you intake and exhaust off, pull the carb off of it. Take rags and roll them tight to block the ports that connect to the engine. Wrap a rag on an air blower and blow it in the carb opening, listen for air blowing through into the exhaust side of the manifold creating a vacuum leak. A more thorough test would be to get tapered plastic plugs that will seal the head side manifold ports. Set the manifold with the carb port up so you can fill the intake with water to see if it leaks into the exhaust side. On second thought with that long exhaust pipe welded on there you may be able to angle the pipe at a slight incline with the exhaust ports up to be able to fill the exhaust side with water.
 
Take you intake and exhaust off, pull the carb off of it. Take rags and roll them tight to block the ports that connect to the engine. Wrap a rag on an air blower and blow it in the carb opening, listen for air blowing through into the exhaust side of the manifold creating a vacuum leak. A more thorough test would be to get tapered plastic plugs that will seal the head side manifold ports. Set the manifold with the carb port up so you can fill the intake with water to see if it leaks into the exhaust side. On second thought with that long exhaust pipe welded on there you may be able to angle the pipe at a slight incline with the exhaust ports up to be able to fill the exhaust side with water.
You gave me a great idea? Rotate the engine so that #3 cylinder is at exhaust valve open, fill with diesel fuel thru the exhaust pipe, spin her up and see what happens.
 
You gave me a great idea? Rotate the engine so that #3 cylinder is at exhaust valve open, fill with diesel fuel thru the exhaust pipe, spin her up and see what happens.
I suppose this is in response to this?
Did all the above and now I give up.
??
Understand what I am telling you? A vacuum leak will make a cylinder not respond to a cylinder drop test at an idle. It will do the same if the leak is a crack or breech into the exhaust manifold where the two join to provide exhaust heat to warm up the air fuel mixture for better operation in colder temperatures.
Going back through what was said I see this..
Just a heads up this engine has never run in this tractor before. I purchased it from John over in Woodland Calif years ago for a spare. It appeared to be good but needed a valve job which I had done. My old engine was burning more oil than I could afford, so it was time for the swap.
Did this manifold come on this engine? You checked for a vacuum leak at the carb mount, did you do any checking on the carb throttle shaft bushings? How loose is the shaft in the carb? These can leak vacuum, it would be less of a chance that it would focus the mixture change to one cylinder but anything can happen. Prove or disprove that cylinder 3 is giving any contribution. What does it sound like when you pull the throttle open quickly from an idle? Do it with number 3 wire on and then again with it off. Myself if the sound during this was inconclusive as to if the cylinder is firing I would rig up something I could short out number 3 wire from the seat while accelerating it in 2nd or 3rd gear. This would involve a low tension spring and some string. If you can tell that it is definitely firing number 3 at faster speeds when there is more fuel/air mixture moving in the manifold and less vacuum you can count out problems with the ignition.
 
I suppose this is in response to this?

??
Understand what I am telling you? A vacuum leak will make a cylinder not respond to a cylinder drop test at an idle. It will do the same if the leak is a crack or breech into the exhaust manifold where the two join to provide exhaust heat to warm up the air fuel mixture for better operation in colder temperatures.
Going back through what was said I see this..

Did this manifold come on this engine? You checked for a vacuum leak at the carb mount, did you do any checking on the carb throttle shaft bushings? How loose is the shaft in the carb? These can leak vacuum, it would be less of a chance that it would focus the mixture change to one cylinder but anything can happen. Prove or disprove that cylinder 3 is giving any contribution. What does it sound like when you pull the throttle open quickly from an idle? Do it with number 3 wire on and then again with it off. Myself if the sound during this was inconclusive as to if the cylinder is firing I would rig up something I could short out number 3 wire from the seat while accelerating it in 2nd or 3rd gear. This would involve a low tension spring and some string. If you can tell that it is definitely firing number 3 at faster speeds when there is more fuel/air mixture moving in the manifold and less vacuum you can count out problems with the ignition.
This manifold came from the good running engine. The carb is new. I sprayed starter fluid near and around the intake manifold with no change. Did you see the picture of the new plugs posted above with #1 right to left. I don't understand what I'm seeing there. I can try shorting plug wire remotely.
 
Did you see the picture of the new plugs posted above with #1 right to left.
It looks like number 4 is the only one firing properly. The rest the photo is to dark to give a good assessment, but look like they are seeing a rich mixture which really doesn’t equate with a vacuum leak. Get a new set of plugs. Or clean them with carb cleaner, wire brush then compressed air, do that process twice to each one. You will want to hold a rag over them when you blast them with air, just saying that because when I do it I clamp them in a vise porcelain down. Where is your original carburetor, is there a problem with it? Put it back on and try it. Those new cheap replacement carbs are a gamble. There is a brand called Kipa that the Cub man Grandpa Love says he has had good luck with. As far as the cylinder short out don’t really need that if it is hitting on all the cylinders when it is coming up to speed from an idle. Make a video of revving it up from an idle, do it with them all plugged on then number 3 unplugged then with only number 4 unplugged. Where you at? It’s going to be colder then he77 here for 4 days or so.
And on the manifold check, ya it’s a long shot but to me something is keeping that cylinder from firing at an idle. It could be the spark plug. But for me I would have to eliminate a problem with the manifold. It may have been fine before but when you had it off jostling it around the last thin piece that was sealing the breech may have been knocked loose. I know it is a lot of “what if” but sometimes that is just part of the diagnosis. I really don’t think you have a spark problem, but your spark needs tested with an “adjustable gap” tester set to a 1/4” as shown in this link. It takes more voltage to fire a plug under compression pressure than it does in open air. Example Spark tester
 
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It looks like number 4 is the only one firing properly. The rest the photo is to dark to give a good assessment, but look like they are seeing a rich mixture which really doesn’t equate with a vacuum leak. Get a new set of plugs. Or clean them with carb cleaner, wire brush then compressed air, do that process twice to each one. You will want to hold a rag over them when you blast them with air, just saying that because when I do it I clamp them in a vise porcelain down. Where is your original carburetor, is there a problem with it? Put it back on and try it. Those new cheap replacement carbs are a gamble. There is a brand called Kipa that the Cub man Grandpa Love says he has had good luck with. As far as the cylinder short out don’t really need that if it is hitting on all the cylinders when it is coming up to speed from an idle. Make a video of revving it up from an idle, do it with them all plugged on then number 3 unplugged then with only number 4 unplugged. Where you at? It’s going to be colder then he77 here for 4 days or so.
And on the manifold check, ya it’s a long shot but to me something is keeping that cylinder from firing at an idle. It could be the spark plug. But for me I would have to eliminate a problem with the manifold. It may have been fine before but when you had it off jostling it around the last thin piece that was sealing the breech may have been knocked loose. I know it is a lot of “what if” but sometimes that is just part of the diagnosis. I really don’t think you have a spark problem, but your spark needs tested with an “adjustable gap” tester set to a 1/4” as shown in this link. It takes more voltage to fire a plug under compression pressure than it does in open air. Example Spark tester
I have given up on this post.....how does he KNOW that the plug isn't firing? I may have missed that little tid bit
 
It looks like number 4 is the only one firing properly. The rest the photo is to dark to give a good assessment, but look like they are seeing a rich mixture which really doesn’t equate with a vacuum leak. Get a new set of plugs. Or clean them with carb cleaner, wire brush then compressed air, do that process twice to each one. You will want to hold a rag over them when you blast them with air, just saying that because when I do it I clamp them in a vise porcelain down. Where is your original carburetor, is there a problem with it? Put it back on and try it. Those new cheap replacement carbs are a gamble. There is a brand called Kipa that the Cub man Grandpa Love says he has had good luck with. As far as the cylinder short out don’t really need that if it is hitting on all the cylinders when it is coming up to speed from an idle. Make a video of revving it up from an idle, do it with them all plugged on then number 3 unplugged then with only number 4 unplugged. Where you at? It’s going to be colder then he77 here for 4 days or so.
And on the manifold check, ya it’s a long shot but to me something is keeping that cylinder from firing at an idle. It could be the spark plug. But for me I would have to eliminate a problem with the manifold. It may have been fine before but when you had it off jostling it around the last thin piece that was sealing the breech may have been knocked loose. I know it is a lot of “what if” but sometimes that is just part of the diagnosis. I really don’t think you have a spark problem, but your spark needs tested with an “adjustable gap” tester set to a 1/4” as shown in this link. It takes more voltage to fire a plug under compression pressure than it does in open air. Example Spark tester
I'm in Granite Bay, California 95746. It's near Sacramento area, and it's going to be cold here also. Low of 35 deg F and a high of 59. I can swap carbs and plugs with the other Cub for test. The plugs were new before test run and picture. I keep thinking I put governor back in wrong, but everyone said no way. Stay worm and inside. I have to get a Super C back together then I'll look at the Cub again.
 
I have given up on this post.....how does he KNOW that the plug isn't firing? I may have missed that little tid bit
Did you see the video posted above? Check it out, pulled #3 plug wire, used a screwdriver to show spark, no engine sound change, multi wires plugs also.
 

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