Is there a practical way to test the magnets while they are still mounted on the flywheel? As the magneto seemed to work just fine before I tore the engine down, I'd prefer to not disturb them any more than necessary.
Any hints for how to check them out? This motor will be running a stock ignition setup and I'd like to have the mag up to snuff.
Walt, if you don't know the history of your flywheel you really should replace the brass magnet screws. Some replace the spools also. I sand blast each spool and then inspect them. Older brass screws heads are brittle and break off. Parts come loose when that happens and and things get damaged, then you get to do the job all over again.
With that being said, there are a number of people I've spoken with that sit the assembled flywheel on an old mag ring and charge all 16 magnets at one time. You would need 24V-36V DC (3 12V car batteries in series). You would need to determine with a compass the N poles on the flywheel magnets and the N poles on the mag ring while very briefly energized. Sit the flywheel on the mag ring. When charging the magnets you'll just do a series of "flashes" to the mag ring to charge the magnets.
I have some history with the car and flywheel. I'd helped the prior owner learn about T's after he got the car and then I got it when he decided he was more of a Corvette and Porsche type. I put several hundred miles on it before things started to go bad.
The motor is as near original as I've encountered, it's a 26 with a standard EE crank, standard size steel pistons and 2 piece valves. It shows very little wear except on the # 1 & 2 rods that suffered when the internal oil line was partially clogged. It will have a larger internal line as well as an external oil line when it goes back together. The car ran great but the rods started knocking and thus the tear down for a full rebuild.
I'd read the threads about charging the magnets in the car, never thought about doing it this way on the bench. I've got an old but functional mag ring sitting under my bench that came from my speedster motor so it would be easy to give this a try.
Here is an interesting magnetic strength meter I was able to find at a flea market a few years ago which I find VERY helpful in determining the "Relative" strength of magnets. It gives a reading, + or - depending on the polarity, and a numerical relative field strength. I have attached a popsicle stick to the unit to hold it a constant distance from the magnet being checked, knowing that magnet strength varies with the distance from the source. Perhaps you, or others in the magnet charging process, might be able to find one of these unique meters.
When flashing the magnets as Kenny described after finding the north and south poles on all of your magnets and field coils make sure to place a north pole from the field coil onto a south pole magnet, (Opposites attract) and then flash. This method works very well, I have been able to lift the entire transmission with the field coil ring after flashing.
My curiosity got the best of me so I Googled the name on the meter and found that the meter I have is precisely calibrated in Gauss and is available for $35.00. A bit pricey for a one-time use, but a worthy tool for magneto rebuilders or lend item for your local club.