Everything ran fine, until I added new parts...

[MikeEyre74]

I am completely at a loss as to what happened here.

My 1949 Cub had run fine for several weeks after I got it going with a Wico magneto and a newly rebuilt IH carburetor. Everything else is stock. I got a 1948 “parts tractor“ in because it had a Woods mower deck on it that I wanted. We Took the magneto off the parts tractor, a J4, and put it on the bench and found that it put out good spark, so I took the Wico off the 49 and installed that J4 from the ‘48. It ran like a top and worked quite fine for several weeks. Then, my order from Brillman Co. came in with a coil and some other pieces that I had intended to put on another different J4 that I had on the bench that had a bad coil and insulator and such. That was the magneto that was going to go in to my tractor when I didn’t have a “parts tractor“ already… so, the coil went into the spare magneto on the bench, along with all of the rest of the pieces, and… There was no fire when we spun it. We started swapping pieces back-and-forth between this coil and the J4 magneto on the running tractor and the only piece that made any difference was the coil. When I put the new coil in, things stopped working. I figured it was a bad coil, so I called Brillman and spoke with the technician there who figured, after swapping everything over that I had, it made sense to him that perhaps it was a bad coil? He told me he was going to send me one out and he did. It arrived yesterday, and I installed it into the magneto on the bench. Again, no fire. In a fit or irritation, I grabbed onto the wire before the spark plug end and as I turned it I felt electricity pretty good… But it just won’t make a spark. I tried several different spark plugs. Even a new one. Nothing.

To ease my pain, I figured I might go for a cruise around the block on the curb, which still ran quite fine because it was equipped with the working magneto… But when I went to start it, which I do with the crank, I got no joy. For some reason, this one is now down and out. It’s spotters, but it will not run. I took the carburetor apart, and checked that there is spark at all of the plugs, but it just will not run.

Two things:

For the mag on the bench, I find it hard to believe that there are two bad coils in a row. I know it makes some electricity, but just not enough to make it work to spark. What is next? The gap is correct on the points, it makes electricity prior to the spark plug but just not enough. The coil(s) are new. I’m at a loss.

Second thing: if I have fuel, compression, spark… And I’m breathing air in the garage, what am I missing on this formerly running Cub?

As an aside, I will mention that the Brillman Co. Has been nothing short of brilliant with their customer service and the way they have handled everything. I will certainly be a customer of theirs in the future. I’m going to have to talk to the technician there again because now I have to send at least one of these coils back because I am pretty convinced that they are both OK… But I need to figure out what I need to order from them to make things happen again. Both of the condensers that I have on hand are not new, but at least the one that was in the running machine beforehand functioned fine up until yesterday. I find it hard to believe that it suddenly just gave up the ghost all of a sudden like that, and that it simply won’t run at all if I’m fact the condenser is “bad”. But perhaps I’m wrong.

Any ideas?

[Glen]

Hi,
Too bad the magnetos have quit working.

You could check the insulation piece in the side of the IH magneto, they get old and crack, then it can short there.
Below is a listing at TM Tractor for new insulation.

http://www.tmtractor.com/new/el/957fp.htm

The insulation is not metal, tighten the nut at the end of the points spring gently, to not break the insulation.

If you put in new points, and the magneto won't work, look at the points closely, they might have a clear coating on the point surfaces, that will not let power through them. File the coating off.

[MikeEyre74]

The post and the insulators are new. I’ve check with an ohm meter and they are isolated from each other. The points are not new, but they’re not old either. They were filed and gapped correctly several times. It’s sputters almost every time I turn the crank, sometimes 2-4 revolutions, but it just won’t catch. I’m thinking that the magneto and the engine running are two different things. The spark is good in the magneto that is on the tractor, but there is no spark in the magneto on the bench. But that has no impact on the tractor that was running, that now isn’t.

[Waif]

A condenser may have failed you?

[MikeEyre74]

But I can see good blue spark at the plugs and my spark checkers flicker properly as well. Will a condenser have that much effect? I was under the impression that they “smooth out” the firing of the spark and keep the points from getting burned... am I not understanding this correctly?

[Waif]

No. If you are getting good spark at plug tip you're doing good.

I'm tryin (and not suceeding ) to keep up with whish whish is which here.

If you have good spark ,check your plug gaps again and go on to fuyel qyuality.

[MikeEyre74]

I’ve had that carburetor apart three times this weekend so far. It’s not plugged up. That gas is from my mower can and it gets run through regularly. Fuel comes out the carburetor when you crank the engine but doesn’t leak otherwise when you just leave it be. I’m totally at a loss.

[Glen]

Hi,
You could pull the Cub on level ground, and see if it will run.

If you get it to run pulling it, it might work using the starter or crank after that.

The people on here have said use a long chain or cable from the drawbar to the tow vehicle out in front of the Cub.

A bad condenser will usually make the engine run bad, or there will be no spark.

[Rick Spivey]

Just a thought (suggestion). I've now run into two different magnetos where the armature (maybe not the correct term, but the rotating portion) had lost most or all of its magnetism. In many magnetos, the field is made of magnets and the armature has windings. A J4 is a bit different, in that the armature is magnetized permanently (I believe the material was called alnico for aluminum, nickel, cobalt), and the windings are the stationary field. In both of those cases you could tell the core was weak when you rotated the core; usually it will "snap" to the "home" position of the magnet, but these bad ones would rotate right on past that point with little or no effort. Don't confuse my "snap" term with anything to do with the impulse coupling, I am talking about the core rotating somewhat on its own to find its home position. I hope this is clear enough, someone more technically competent could probably describe it much better, in the correct terms. Anyway, check to see if your magneto has lost significant magnetism. While I have had other people tell me they can be re-magnetized, I don't know how it is dome on this configuration, or what too is required to do it. I simply get one from another magneto and replace the bad one.

[MikeEyre74]

I got it to run once yesterday, and I ran it for a good long time just to get things warmed up and burn off any deposits and make sure everything was up to working temperature and all. And when it shut off, it just wouldn’t fire back up again even though it was warm.

As far as the magneto goes, I have had two different magnetos on here at various points and both of them worked just fine. Unless something has happened to some internal part on the magneto, I don’t understand why it would just not work? It’s not like it doesn’t have a good blue spark. It jumps about a quarter of an inch from the plug wire to the block when I crank it over, for instance. I just don’t feel like it’s the magneto… I think it’s something else that I’m missing?

[staninlowerAL]

Check the rotor and pinion for loose motion due to wear. It is possible for these parts to wear enough to affect the timing or even jump to a different position. It's not common but can happen. BTDT

[MikeEyre74]

Ok. I’ll check that later today then if time allows. I know we took one of them apart to clean and grease it but this other one got left alone because it was runnning fine.

[staninlowerAL]

Also double check the plug wire positions. Easy to get them in the wrong position when swapping things around. Verify the compression, stuck valve(s) will make starting difficult if not impossible. Just went through that with a '52 that had not been started in a while.

[MikeEyre74]

This part I know is correct. I’ve pulled all the plugs and have compression (that I can feel by hand) and then followed the spark from plug to plug in the correct firing order. And again, it did start and run ONCE yesterday. Ran fine as long as it got started... I think the problem is just starting it. Once it gets started, it runs fine… That’s why am starting to suspect a carburetor issue? But I’ve had apart and I can see that it has fuel and seems to be working correctly...

[inairam]

Could you be 180 degrees out on the timing?