Farmall cub magneto issues

[redalert1466]

I’m working on a 1947 farmall cub, it hasn’t ran in 40 or so years,I’ve never personally had it running, when I started working on it it had no spark, I sent the magneto to a friend and had him rebuild it,at the same time I installed new plugs and wires, since then I have still not been able to get it running, I’ve been through the whole process of timing it according to the manual, and Wisconsincubman’s YouTube videos,both front pulley and govener marks line up at tdc,I have good spark now, however it dosent even attempt to start, backfire,nothing. at what should be correct timing,according to my timing light it’s at about 60 degrees advanced if you pull the magneto closer to the block you can get it to about 38 degrees advanced,the timing marks on the rotor button and the pinion gear that turns it are lined up, is there anything else on this thing that can make it out of time?

[Powered by IH]

Make sure that cylinder #1 is on TDC when the timing marks line up.

The magneto should trip and spark at #1 TDC for the #1 spark plug. If you don't have any spark at that plug then make sure the rotor in the magneto is pointing at #1 cap end. You can put magneto 180 degrees out of time accidently.

Make sure you put the wires on correctly. #1 on the cap is labeled, then clockwise it goes 1,3,4,2. #1 goes to #1 spark plug, #3 goes to #3 spark plug, etc.

I know you may already know this but it doesn't hurt to double check.

Does it always spark way before TDC? I would recheck the points gap too as that can affect timing.

[snoshoe]

Is the impulse clicking on this thing or not? When you are getting these advanced readings is the impulse clicking?

Another thing. Have you checked that you actually have compression and the valves are not stuck open?

[HydroTek]

Do you have the hand crank ? -- makes this easier
not difficult to make a crank if you need 

Remove the spark plugs and lay them on top of the head
reconnect the plug wires

Turn the engine observing the two marks on the crank pulley
the mag impulse needs to click on the second mark
and make spark at number one plug 

Put a finger or thumb -- whichever fits
Over the spark plug hole on number one cylinder
-- rotate the engine until you feel pressure
This is number one compression stroke

The mag should be making spark at the second line and firing the plug at this time 

This will occur on number one cylinder , every other rotation of the crank pulley 

[jass1660]

You say good spark but no fire, are you sure it’s getting gas?

[rustred]

15 hours ago, redalert1466 said:

I’m working on a 1947 farmall cub, it hasn’t ran in 40 or so years,I’ve never personally had it running, when I started working on it it had no spark, I sent the magneto to a friend and had him rebuild it,at the same time I installed new plugs and wires, since then I have still not been able to get it running, I’ve been through the whole process of timing it according to the manual, and Wisconsincubman’s YouTube videos,both front pulley and govener marks line up at tdc,I have good spark now, however it dosent even attempt to start, backfire,nothing. at what should be correct timing,according to my timing light it’s at about 60 degrees advanced if you pull the magneto closer to the block you can get it to about 38 degrees advanced,the timing marks on the rotor button and the pinion gear that turns it are lined up, is there anything else on this thing that can make it out of time?

problem probably stems from removing the mag. and sending it out to whoever worked on it.  in most cases the points only need to be cleaned and gapped and can be done without removal. that is how these no start problems start.  who knows what he did or if its assembled correctly. have you squirted some gas into each plug hole to see if it actually snorts farts or starts ? have you checked the compression ? have you checked the valves for being stuck ? your working on it ,... but what are you doing to it ? info , info is needed.

[560Dennis]

Check your cub rotor position and compare to the attached links description.

 

https://farmallcub.com/community/threads/timing-j4-rotor.83108/

[redalert1466]

The impulse clicks,All 4 cylinders have good compression, no valves are sticking,we’re getting gas,to make sure I did dump a little gas in the cylinders,the only time it sounds like it wants to try to start is when the mag is retarded as far as you can get it, it will spin slightly faster like it wants to, but It never gets there,just to try somthing I bolted it on 180 out, it would backfire, but when you line it up on the marks and time it correctly it won’t do anything, just puff a little white smoke from the exhaust while cranking, I didn’t have time to mess with it tonight but I’m going to try to dig into it a little more tomorrow evening, I’ll let y’all know what I find

[rustred]

14 hours ago, redalert1466 said:

The impulse clicks,All 4 cylinders have good compression, no valves are sticking,we’re getting gas,to make sure I did dump a little gas in the cylinders,the only time it sounds like it wants to try to start is when the mag is retarded as far as you can get it, it will spin slightly faster like it wants to, but It never gets there,just to try somthing I bolted it on 180 out, it would backfire, but when you line it up on the marks and time it correctly it won’t do anything, just puff a little white smoke from the exhaust while cranking, I didn’t have time to mess with it tonight but I’m going to try to dig into it a little more tomorrow evening, I’ll let y’all know what I find

its out of time then. get number one cyl. on compression then turn the engine slowly and see where the timing marks are. that will tell you the story. sounds to me like your guessing and  not confirming the timing is correct.

[rustred]

Just now, rustred said:

its out of time then. get number one cyl. on compression then turn the engine slowly and see where the timing marks are. that will tell you the story. sounds to me like your guessing and  not confirming the timing is correct.

turn the engine over slowly till the mag trips is what i wanted to say. and stop there and look at your timing marks.

[HydroTek]

2 hours ago, rustred said:

turn the engine over slowly till the mag trips is what i wanted to say. and stop there and look at your timing marks.

2nd and 3rd post in this thread

the OP has not addressed impulse timing as far as we can tell 

[Binderoid]

One thing you have to remember is if you turn it 180⁰, you only  get 90⁰ at the rotor. So if it's really  180⁰ out,  that's  two full turns of the impulse. 

Unless you're certain  where its at, start over with  no.1 TDC on compression. Next, aim the rotor  at no.1 wire. Install  the mag on the engine. Turn the  mag so the coil is all the way possible  toward the engine. Crank the engine two full turns and stop at TDC again.  Now carefully  rotate the entire mag to the right until it snaps (make sure  it's  grounded so it doesn't  bite you). It is now in time enough to start.  

[Binderoid]

Also, if it's  been sitting  40 years you need to  squirt oil in the cylinders,  they are dry and interfering with  compression... even  though it  feels  like it ought to have enough  compression  to  start. Honestly,  I don't  really  know why this works,  but it is the absolute magic  bullet  when  trying to  start any stubborn Wisconsin. 

[HydroTek]

I would suggest at this point to remove the mag and start fresh
Determine compression stroke on #1 by the thumb over the hole method
Turn the crank pulley to the second mark

Then we look at the rotor on the mag
it also has to be timed to the impulse
there are marks on the rotor and drive gear

Rotate the mag backwards until the rotor is pointing to #1 on the cap
(you should feel the magnets align)
This will be the position you install the mag

Rotate the engine by hand until the pulley lines to the second mark
-- the impulse should snap here -- if not turn the mag a little

The pointer on the mag rotor will only point at #1 every other rotation of the engine
-- but if you installed the mag as I described above 
this is of no concern 

Main point is to get the mag to "click" on the second mark each time it comes up 
-- lay #1 plug on the head with the wire attached to verify you have the mag timed 

The drive gear for the mag can come out and get out of time
-- seen this happen way too many times
Not to worry tho
with the rotor pointing to #1 and the magnets aligned as described above
the drive gear should align with the nubs on the mag 
-- crank pulley on the second mark
move the gear so the mag nubs will align