TOPIC: Any input on Magneto rebuilding 59 evin 450

Like what typically goes out in a magneto? I'm not getting spark and have ruled out everything except the magneto. So SHould I rebuild it and what do I look for. I can get the parts here in seattle. its a 59 evinrude 450 50 hp. 4cyl.

Most likely problem would be the points. Pull the points, clean them to bare metal and polish with crocus cloth or something like 1200 wet/dry; if they don't have a lot of pits they should be serviceable. Set gap to .020".

Second problem these have are rotors that short to ground. So your spark zaps right thru to the magneto shaft instead of making your plugs spark.

You can troubleshoot this problem by removing the ignition cap, pulling the rotor, and with the shaft of a screwdriver firmly on the metal magneto case, tip close to the mag shaft where you just removed the rotor, spin the mag in a clockwise (viewed from top) direction. You should have a hot, blue spark snapping from the mag shaft to the tip of the screwdriver, if it's good it'll jump at least 3/8-1/2".

If you're not getting spark at the plugs, but it does spark from the mag shaft, the rotor is bad.

Third problem is a bad coil. You can remove the coil and do resistance checks and an inspection for burn marks.

The most problems I had with old V4 mag coils was that they would spark well when cold, but after they heated up the engine would die and wouldn't restart until completely cooled down. Repeat this cycle over and over again, until you figure out that it's the ign coil causing the problem! And every used coil I could scrounge up had the same problem. Installing a brand-new coil fixed the issue.

Don't know if you can get aftermarket V4 mag coils anymore but Seaway Marine in Seattle probably still has them in stock.

BTW it's quite easy to service the points without removing the mag, just be sure to line up the timing marks before loosening the mag mounting bolts & removing the belt. The driven pulley is a slip fit on the mag but may require a little "persuasion" depending upon how long it's been on there and how much corrosion.

Before tearing into the mag, one thing you might want to do is pull the "kill" wire from the motor's wiring harness, connected to the side of the mag. If this wire is shorted to ground or the ign switch is bad, it'll kill your spark. Just remove the wire and re-tighten the terminal. If you still have no spark, the problem lies within the mag.

I would definitely try points service first, then dig into the bowels of the mag as required.

HTH & let us know what you find...........ed

p.s. pretty nice boating weather up here, summer finally made it!

I had two of these motors. One I had to put in a new coil. They can be spendy but can be found. Not a hard mag to work on. I have seen the complete mags go for $150 and up coils $80-ish give or take.
That mag is not much different than the fairbanks 4D used on merc's