3 hp sumpter plugoscillator?

[Brickman]

1918 3 hp fm with sumpter plugoscillator # ? , how much voltage shoud it put out ? if i unhook the mag wire and put it on a digital volte meter it shows
0.08 or less than 1 volt, while i have the engine running with a battery and low tension coil . if i use a automotive coil it gets real hot fast , if i use this
outher big coil i have it will run at least a hour and never even get warm
i am useing a car jump starter pack for the battery . if you look at my outher post , 3 fm you can see the coil setting on the creaper seat with the battery pack . if i unhook the coil and battery with engine and hook up the mag wire
it will not fire all the time and cut out and run real bad any ideals please
thank you ron brown in central il

[Elden DuRand]

Well - let's see here......first things first.

The reason your low tension oscillating magneto doesn't show much voltage at the output is that it is AC and transient in nature. That means it won't show up as much on a digital or analog voltmeter. You can actually see the sinusoidal waveform of the magneto output if you use an oscilloscope.

The reason your automotive coil gets hot quickly is that most mag fired ignitor systems have the ignitor points closed at all times except just at the time of firing. This means that the coil draws current from the battery most of the time and, since it is a low resistance, it will draw lots of current and get hot.

The other coil you're using has a higher resistance, thus doesn't draw as much current and, as a result doesn't get hot.

Too much resistance, though, and the coil will not produce enough voltage when the ignitor points open.

I think that an adjustment of the ignitor points might help. The points should be closed until hit by the "hammer" at the time the mag trips. If there's too much gap between the hammer and the ignitor trip, the magneto field will have collapsed (or not built-up) enough to give a hot spark.

If adjusting the hammer gap doesn't do the trick, you may have to have the magnet(s) in the magneto recharged.

Now - someone needs to jump in here and make the appropriate corrections on accounta because I'm not real familiar with the Sumpter system and am just ass-u-ming

Oh, yes - I did a study of low and high tension magnetos. Go here to get the rest of the way confused.

http://home.cybertron.com/~edurand/O...therstuff.html

Take care - Elden
http://home.cybertron.com/~edurand

[Preston Wells]

Eldon if I remember right my 3hp Z has a Sumter plugoscillator and the pionts remain open until the striker moves the hammer against the torsion spring into a momentary closed position from which they break and create spark. I think the voltage on my mag was about 1.2-2 volts. I did have a problem with timing this mag when I was working on it several years ago and had to do quiet a bit of trial and error adjusting of the striker to get it to fire right . Good luck.

Preston
FL

[Brickman]

eldon i had a older gentleman charge the magnets , he has been in the engine hobby for years , i can feel the magnatisum ? when the mag is turned by hand when it is on the bench amd he says that should be fine.
i did have a big gap between the hammer and ignitor trip so weld the igniter trip up some because it looked wore the most , and it did run a little better
it still has about a 3/16 gap and when the hammer hits it i cant see it move very much at all , so maybe it is not opening the points enough , but i dont know when it comes to this i am all messed up! i am sure the timeing is ok with the mag amd the exaust valve. i still can use all the advise i can get !
i looked at your web page on ignitions GOOD JOB eaven though i dont understand most of it , or why one coil will get hot and not the outher one.
so all advive is welcome and much appreciated .
ron brown in central il---- with not much spark . THANKYOU !

[Elden DuRand]

Well, I guess I was -almost- right about the Sumpter set-up.

If what you did to the hammer made it run better, maybe a little more of the same will improve it more.

I'm sure someone out there knows the correct gap for the hammer. If the ignitor points are hammered closed, I'd think that as long as there is -some- clearance, it should work fine. Too much and the points won't open enough.

I guess!

Take care - Elden

[Brickman]

a big thank you to every one that replyed , i still cant get it to run right with the mag and igniter , only with the battery and low tension coil so i will send it off to hit&miss on monday. thanks again ron brown in central il

[oldironcollector]

Ron,

Don't feel bad Fairbanks could'nt get the plugoscillators to work right either for long! There were thousands of engines converted by Fairbanks themselves to other ignition's from the Sumpter set-up . I have been there and done that myself and spent way too much $$$ trying to get one to work dependably , I have seen some that work like a charm but never could get the one I had to go . I wish you the best of luck on it! and please let us know how it works out.

Denny

[joebiodiesel]

I've got a 3HP and a 6HP, and neither one of them came with an ignitor. I've never been able to find a Sumter Plugoscillator for a reasonable price. If you're not using the original mag, what are you using? I was thinking of making it a hot tube ignition.
Any replies apreciated.
Joe

[MarylandSteam]

The insulator tube gets worn/burned, especially if it is loose it will rotate and intermittantly fire to ground causing these symptoms. You will need to rebuild the ignitor or have it done, the main part to replace being the insulator tube that the movable point rotates in.

Also make sure you always unhook the magneto wire before you switch to battery/coil, if you connect the battery/coil setup at the same time the magneto fires it will fry the magneto.