I've been compiling these articles for almost three years now, and so far, I've carefully avoided one particular subject. That's because all the first hand knowledge I have about this harmless-looking engine part was gained when I witnessed an incident way back when my husband and his brother were restoring their first engine. As they examined this particular part closely, and tested it out, the dog had the misfortune to be standing a little too close. There was a small blue flash, a shout of surprise from the human members of the group and the canine one yelped and shot to the far end of the garden, where he remained shivering with fear for some time. He's a very intelligent dog, and I decided to take his advice on this one! Thanks to his wise counsel, I've never fallen for the "just hold this wire while I make a test" trick, but when it came to choosing a subject for this month's article, he was more interested in his biscuit box than offering constructive suggestions. So, given that the advice given via the internet stationary engine mailing list came from two of the most respected sources we have in our group on the subject of ignitors and magnetos, namely Ted Brookover and Bill Lopoulos, I decided I would be safe.

With something of the same feeling of trepidation I have beginning this article, the original question came from someone taking his first serious look inside a magneto.

*
Well I've decided to venture into the world of electromagnetic flux and disassemble an ignitor and Webster mag. This one got REAL wet at the Pendleton show a couple of weeks ago. The ignitor was puffing around the rotating shaft too so it seems like a good thing to jump into it.
Successfully fixed the leaking shaft with a dab of valve lapping compound and some oil on the tapered fit.
Next I thought I would take one of the end plates off the Webster to see what makes it tick inside and to check for a damp coil(s). Decided the spring end might be the best end to remove. I pulled the springs off and was surprised to find that the "spring rocker" was not located at "magnetic center". In other words, the pins on the spring rocker are not
horizontal when the poles and coils line up to their natural magnetic alignment.
To get the end plate off I need to remove the spring rocker. Is this a taper self locking fit? No pins or keys? When I reassemble this, should the spring rocker be aligned with magnetic center, or is there some special angle that it should be installed at?


The first response was from Ted:

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Try moving the movable electrode in the ignitor side to side, if there is any movement at all, you might as well fix it cause the mag and the ignitor are going to be "out of time".
The magneto inductor has a woodruff key on each end of the shaft to locate the spring arm and the push finger. The key way can be hard to find if the key is sheared off, but it is there.


As ever, the answer to one question raises another.

* J
udging by the feel of it I would say there is .002/.003 clearance between the movable electrode and the ignitor body. Is this OK?

When removing the spring arm and/or the push finger, is this fit a tapered fit or a cylindrical press fit? Had no luck removing last night, but I am treading gently. May need to make a small puller...

* If the side to side movement is visible, it is too much, the problem is that when the push finger on the magneto is released and strikes the movable electrode lever, the first and "only" movement should be a rotary one that opens the points.
If the shaft is worn, the first movement of the movable electrode shaft when struck will be a "Lateral" one to take up the ware and then the second movement will be a rotary one that opens the points.
Unfortunately, peak voltage in a Webster only occurs for a tiny fraction of a second, so by the time the secondary movement of a worn shaft opens the points, the voltage peak has passed.
It is at this point that many Webster Mags are declared "Junk" and out comes the batteries and coil. Then I hear this, "It must be the Mag, the engine runs fine on a Battery and Coil"..... sure it does, the voltage from a battery and coil is constant and controlled by the points making contact and breaking contact. The really sad part here is that every time a Webster rig fires on a Battery and Coil, it suffers DAMAGE ! The points on Websters are soft as are all low tension "magneto" points; the voltage of a battery and coil will burn them.
And every time the rig fires with that coil laying right under the Magneto it builds a huge ( several feet in diameter) magnetic field. If that field is strong enough and if the polarity is opposite that of the Magnets on the magneto, the magnets can suffer. Disconnecting the wire does no good, this is Magnetism not Electricity, they are different like Air and Water.
Yes, you must use a "Puller" on the spring arm and the push finger, they are a tapered fit with Woodruf keys, and the side plates are very fragile.



*
I have found that the battery terminal puller that you can get from Sears works very well. Of the countless Websters that I have serviced, only one or 2 have been so stuck that this puller will not do the job.
Back the nut off the shaft so that it is flush to the end (to protect the threads). Put on the battery terminal puller, tighten the jaws, and tighten the puller lead screw. You will need to give the end of the puller several sharp raps with a hammer to loosen the push finger/return arm/bump arm.
When pulling ends off the armature shaft, be careful that you don't crack the pot metal bearing plates.
When rebuilding the igniter with a worn movable electrode, you will frequently have to replace both the shaft and the seat/guide. That will ensure a good seal. Make sure that you cut a 45 degree seat on the electrode after replacing the shaft. After cutting, seat the electrode with valve grinding compound.


The "professionals" are not the only ones to take a look inside a Webster.

* I completely dissassembled my Webster to include removing (very carefully) the coils off the iron cores. I also removed the oil wicks and cleaned them. She was totally in pieces. Went back together easy. By the way, I also checked the armature to make sure it hadn't contacted the fields (wrong terminology I know), but you know what I mean. I kinda swagged "TIR" on the shaft. "Yea, that looks about right"
Ted, If you read this...adjusting the movable ignitor contact on mine doesn't seem to make any difference. It seems to run ok. especially after I got the cam gear timed in the ball park. Is there any way I can put a meter or something to tweak it?
I just remembered, that pushing in, against the spring, on the moveable contact, scrubs the contacts clean. Read that somewhere. I try to remember to do that before starting my Galloway. I've also got to find a better way to lube the moveable shaft. Primer cup is in the way. Possibly grease it with a needle point.
I also remembered something else - use new lockwashers. The one on the moveable contact on mine was too tired and the nut came off, after running 15 minutes.
I got new hardware, new rollers and trip lever. I also used CS screws on the end plates i.e. bearing plates and round headed screws on the other do-hickey plates. One screw on that plate could have used a little counterbore.

Do your magnets "bottom out" on the laminated sheets? On my 2 magnet Webster the outer U magnet is about 1/8th inch from touching the laminates. May adjust this if advised to do so.
Also advise checking the North and South on the magnets with a compass...In case someone in the past has gotten them screwed up.
Good Luck, "Websters are really Cool!"

* It is the inside face of the magnets touching the laminations that counts, not the bottom edge. Most multi-magnet Webster mags have a small gap at the bottom.


This section of the saga finished with

*
Thank you all for the Webster and ignitor tips. I'll pick up that battery terminal puller on the way home tonight. Can't wait to see what's inside!

One of the fun aspects of communicating by email is that the story gets updated quickly, an it was only the following day when we heard how the project was going:

*
Picked up a battery terminal puller last night and removed the spring arm and disassembled the Webster. Pretty simple in there! Just two coils and the rotor. Why are there 4 poles on the rotor when only 2 are ever used?
De-oiled everything. Previous owner was a little overzealous with the oil can. Disconnected the ground on the coil set and checked insulation leakage. Measured infinity on the megohm setting. Total coil set resistance is about 9 ohms. Is this about right?
Bushings in end plates were in good shape so I put her all back together. Got a pretty blue spark again. Put it back on the engine and fired it up about 10:00 last night.

I didn't mess with the set screw adjustment on the ignitor arm that the trip arm hits because it is working so well. Is this gap setting a constant on all Webster/ignitor setups? If so, what should the setting be? OR is it 'tweeked' to give the best spark.
Thanks again for all the great support.

* I'm not sure what the narrow poles are used for, they may act as magnet keepers in case the armature snaps too far, that would allow the magnets to partially discharge.
As for the bump arm setting, I have seen some lit say that it should just touch the push finger, others say there should be a .010 gap. I would just adjust for maximum spark.
9 ohms is about right for coil resistance, but I would never expect there to be a break in the coils. The way that they fail is 2 part. First the varnish insulation cracks and they spark between layers when the voltage builds up. Secondly, they spark through the insulation on the wire that goes to the terminal block, again due to cracks in the insulation. You will never be able to detect these problems with a meter. I always just replace the coils, you have gone through so much work in disassembling the mag, you
should just put new coils in. Especially in M and MM mags, those coils are never any good. K & L coils aren't too bad. If you remove the coils for any reason, don't even think of putting them back in. Disturbing them will cause too many cracks in the insulation.


So, there you have the advice of experts, and if this article is not helpful, just blame the dog!

stationary-engine@atis.net

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