Hey guys, im new to the forum and also new in this world of restoration. I recently picked up my grandpas 1948 B and want to restore it and bring it back to its old glory. Got it home, and surprised to find i had not problem cranking the engine, so that was good news. After doing some minor maintenance in order to get it ready to try to start, i found that my magneto was cracked and completely corroded inside. I was able to relocate a used magneto that stated it had spark so i purchased it. Sadly no spark.
Bought a new cap, new plug wires and new rotor. Still no spark. Im new to magnetos but online searching is telling me that it could be the coil or the condenser. Anybody have any thoughts on the best way to test these two items.

Glad it worked out.

I got it. Thanks for all the help. Points needed cleaned and gap set to .015. Got great spark. No carb work. That should be easier. Thanks guys

The crudded up points is a definite possibility. I've
had 3 engines that needed points cleaned this past
summer. I believe it was due to the very humid conditions
which we had.
All 3 were corrosion on the points. Certainly worth looking
into.
Jim

The points are the set of contacts that are mounted on the frame of the magneto below the coil. The condenser is the small metal tube, about 1/2" in diameter, that is mounted close to the points and has one wire coming out of it and is attached to the points. These are the two components that are most often the problem in magnetos. Oxidation can occur on the contacts of the points, this acts as an insulator and prevents current flow. It does not take much to clean that off, a lot of people will fold a dollar bill and run that between the contacts a few times. Very fine emery cloth will work as does a small fine file. The condenser can be replaced, but beware, they are sometimes bad right out of the box.

As John T noted, you need to be sure your impulse is working. When the engine is spinning at cranking speed when trying to start, the magneto is not spinning fast enough to generate enough power to provide adequate spark. To compensate for this, the magneto has an impulse in it. Simply put, the impulse is a spring that is wound up and releases just as the magneto is about to fire. When it releases, the magneto spins a lot faster and that is enough to generate a good spark. When the tractor is running, the dogs that allow the spring to wind up are kept from engaging by centrifugal force. So, as Jon T said, you should hear the click from the impulse tripping twice every revolution of the flywheel. If this is not happening, you will not get spark. Usually the fix is pretty simple, a broken impulse spring being usual culprit.

I would switch to a model X mag.

When they say "points", they're referring to the ignition points. They will look similar to the attached picture. When the main shaft turns, these will open and close. When you locate them you will be able to open and close them by sticking a screwdriver in there. These are the points you need to clean up with emery paper or a tiny file. Hope this helps.

Thanks a ton for the clarification with pictures. i will take a look at all this today. Thanks for the help!!

If my memories is correct the C mag is a two piece point set.

While I have seen many mags coil or condensor fail, a more common cause of no fire are the points are burned or pitted or even just oxide or carbon coated which a non abrasive as possible clean/buff/polish might cure. I have used a clean shop cloth or even a dollar bill dragging it between the points to clean them or if badly burned or pitted dressing them with a points file might get you going. However if they are badly burned or pitted a new set is in order AND CHECK FOR THE PROPER GAP... If its NOT the points a condensor is cheaper then a new coil if you don't have the means to test either of them.

For it to fire at slow cranking speed the Mags IMPULSE ASSEMBLY must be working (the can get clogged or the spring broke or the wind n trip assembly not work) whereby a spring winds up then trips/releases at which time you should hear a loud distinctive SNAP. As you turn the flywheel/engine slowly see if you hear that loud SNAP every 180 degrees ???????????? If not she's not gonna fire at slow cranking speed.

John T

You did not mention points?? Most often when mag set around the point will oxidize and will not make good contact. Point are nothing more than an on / off switch. Clean points contact surfaces with fine emery or file and blow them clean and see if spark returns. DW

I work on them as a hobby. I have the testers and a magnet charger. I can help if you need it.

sure would like tour phone number!!! mine is 812 665 2419

Thanks Guys, all new to me and this all helps. When you guys talk points, i will have to look hard to make sure im hitting all the points. When i think of points, i think of the 2 under the cap that the rotor passes by and the one on the middle of the coil. It does have the snap your talking about, it does wind and snap every 180 degrees so sounds like thats good.

I will keep you guys posted!
Thanks for all the tips!