Farmall cub timing

I reassembled the cub engine after a valve job and now #3 cylinder is not firing. It has spark and compression, but while running i pull the plug wire and no difference. New plugs and distributor cap also. When i installed the governor, I did line up the punch marks. The crank timing marks line up with #1-cylinder TDC to the rotor pointing at #1 wire. I'm at a loss, what am I missing? Is there any chance the I could be 180 out and the engine would still run just missing #3?
 
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Try a different plug. I worked on a Hercules engine for
a mechanic down in Muscatine once & couldn't get
#3 cylinder to fire. It had champion J-8 plugs & one
was shorted----brand new right out of the box. Put
another plug in, & it ran smooth as silk. Soooo--
try a different plug.
Jim
 
If the other 3 cylinders are firing OK it can't be timing - something is wrong on #3. Have you checked to see if you have compression. Maybe a valve not adjusted correctly. You can change the plug with another cylinder and see if its the plug. You can also do the same with the spark plug wire, just not both swaps at the same time.
 
In addition to what others have said. The 3 others all show a change in engine sound when the wires are removed from them? If one other seems suspect you probably have two crossed, 1-3-4-2 clockwise. Otherwise a vacuum leak may be your problem. Spray carb clean, starting fluid or hold the end of an unlit propane torch at the intake to head mating area with the engine at idle a listen for a change in engine sound. Also check the carb to intake gasket for a leak.
 
Update, not a plug or wire. I will try for vacuum leak. #3 has good compression 100#+. Maybe not getting fuel, on my way to check that.
Thanks everyone for the help,
 
Update, not a plug or wire. I will try for vacuum leak. #3 has good compression 100#+. Maybe not getting fuel, on my way to check that.
Thanks everyone for the help,
Quintuple-check that you don't have #2 and #3 crossed up. I speak from experience. Swore up and down they were right. They were right. They were RIGHT %$#@ it! I must have checked a dozen times. Sure enough, #2 and #3 were swapped on the head.
 
I tried 2&3 swap and it ran worse. Strayed starter fluid near and around the intake with no change. The #3 cylinder has good compression. I can hold the plug wire with a screwdriver near the #3 plug and when close I get a good spark, and when removed very little change in engine sound.

See video at
 
Have you checked the valve tappets for proper gap. Maybe the intake valve on #3 is not moving.
Shining a flashlight into the plughole I can see the valves moving. What I have not done is see if they are moving at the right time. It is hard to believe that they are not, but I'm in for checking everything. 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. This engine good sounding and no smoke, just no #3. I think I'll pull another plug wire and call it a JD.
 
If the cam lobes are positioned correctly to fire the other 3 cylinders correctly then it has to fire other 1. The only way is if the cam lobe was ground off set for that cylinder, this is possible but extremely unlikely. At what temperature was the engine when you checked the compression? If it was barely warmed up I wonder if you may have a valve set just a bit to tight and when the engine comes up on temp the valve is being held open. Run it at a higher RPM and short out that cylinder. If you get a change when you short it at a higher rpm that supports the vacuum leak theory. You may also have a worn bushing in your distributor.
 
If the cam lobes are positioned correctly to fire the other 3 cylinders correctly then it has to fire other 1. The only way is if the cam lobe was ground off set for that cylinder, this is possible but extremely unlikely. At what temperature was the engine when you checked the compression? If it was barely warmed up I wonder if you may have a valve set just a bit to tight and when the engine comes up on temp the valve is being held open. Run it at a higher RPM and short out that cylinder. If you get a change when you short it at a higher rpm that supports the vacuum leak theory. You may also have a worn bushing in your distributor.
Thanks, I'll try that tomorrow. Compression taken with engine barely warm. The old engine with the same mag did not miss, just smoked bad. Thanks again,
 
I tried 2&3 swap and it ran worse. Strayed starter fluid near and around the intake with no change. The #3 cylinder has good compression. I can hold the plug wire with a screwdriver near the #3 plug and when close I get a good spark, and when removed very little change in engine sound.

See video at
Wait.......did I read that you can hold the plug wire with a screwdriver and when you get close to the plug you have good spark??? You can pull one wire off a cub and it makes very little difference. We have bought several Farmalls with 2 and 3 plug wires reversed and they ran,you could tell something was off ,but they ran decent.an average hobby tractor owner probably wouldn't notice,just figure it was ok. Are you sure it's not sparking? Other than pulling the wire and listening for a change??
 
Not much of a spark IMO. You running solid core wires? You need to swap the wires and/or plugs to a different cylinder and see if the problem follows the plug/wire, not just switch 2 and 3. Since you havent dont that, or have you and I missed it, Ill assume the plug is bad.
 
Not much of a spark IMO. You running solid core wires? You need to swap the wires and/or plugs to a different cylinder and see if the problem follows the plug/wire, not just switch 2 and 3. Since you havent dont that, or have you and I missed it, Ill assume the plug is bad.
Yesterday I checked and readjusted the valve lash to a loose 15thou. Still same problem. Today I'm going to pull a distributor cap, rotor, and wires from another good running cub and give that a try. I guess the next step would put on a spare mag. What gets me is all electrics worked well with the old engine block. It was just burning oil like crazy. Is there any chance that it could be a head gasket even though it has good compression?
 
The spark should be jumping a lot farther than that. Is the plug gapped right? Did you try another plug? TRy holding the screwdriver close to the block & see if the spark jumps at least 3/8 inch. If not, find out why?
 
Yesterday I checked and readjusted the valve lash to a loose 15thou. Still same problem. Today I'm going to pull a distributor cap, rotor, and wires from another good running cub and give that a try. I guess the next step would put on a spare mag. What gets me is all electrics worked well with the old engine block. It was just burning oil like crazy. Is there any chance that it could be a head gasket even though it has good compression?
Check for a loose distributor shaft as I said in reply 12.
 
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.
 

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