Webster tri-polar: very bright spark, only reads .5 V

FunMobile

New member
I've got a 1.5hp little jumbo with a webster on it. When I take the igniter and mag off I can see a very bright and fat spark, but I cannot get the engine to fire. If I put the voltmeter on it I get between 0.3-0.6 volts ac.

Will a spark still look that good with such low voltage? It's supposed to be closer to 4-6V from what I've read. Lastly, how can I go about getting this magnet charged if I don't have access to a charger? What sort of business would have that capability?
 

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Jeremy Hartle

Subscriber
Any mag shop can recharge. Surely there is a collector in your area that will do it for you. When you say fat and bright im assuming its fat and bright blue. If its orange it probally wont cut the mustard. The voltage im not sure about. I thought it was around 10 volts ac when spun with a drill.
 

FunMobile

New member
Yes, bright blue. I just took the mag off and found the little finger on the back of it hits the oil well if I try to spin it. When I get some time I'll take that off at actually put the drill on it. There is one guy i know in my area, but I've already asked for my share of favors from him so I don't want to bug him anymore.
 
If it sparks it should be good? Did you say you were going to put a drill on the mag and spin it? I don't think that is possible, it just trips..
 
You have good spark off of the engine. That doesn't mean you have good spark on the engine. There adjustments that need done when the mag is on the engine. It's difficult to measure the voltage , points open/closed? Spin the mag , that isn't how it works. You need hands on help. Ron
 

FunMobile

New member
Ok, so it seems I'm getting conflicting advice... I know the mag is designed to spark on a trip, but Jeremy's response led me to believe taking the springs off and putting a drill on it was a good way to test if your magnet charge is still good. Hadn't heard of that on a webster before, but also haven't serviced one of these before...

Since the mag/ignitor comes off all in one unit the only adjustment I can think of that would need to be performed while it's on the engine would be making sure the push rod trips it at the right time. I'll look up how to time a webster mag to make sure that's correct.

Ron, are there any other adjustments?
 

Jeremy Hartle

Subscriber
No you cant spin it with the trip finger on it. If its a good fat blue spark the mag should be fine. Is the spark consistent. Make sure your getting good ground while on the engine. There is a lot of little things that wont let it spark on the engine.
 

cobbadog

Active member
Also double check your spark timing, valve timing and that you have fuel getting to the source of the spark.

If I'm not correct but if you could attach a drill to most magnetos it is not advised unless you can copy the engine speed or rotation speed of the magneto. Spinning them quicker may harm the magneto but will give false hope as to condition of the magneto.

Good luck with your restoration and hope it all works out well for you.
 
If you suspect the mag is bad you can rig a battery and coil to see if the engine will run that way.. Just make sure the points are not closed when you hook it up .
 
If you suspect the mag is bad you can rig a battery and coil to see if the engine will run that way.. Just make sure the points are not closed when you hook it up .
***That is correct , the points are normally open when using a battery and coil then close momentarily when pushed by the push rod , but are normally closed when using the mag. Ron
 
I have a model N. Nelson Bros. The length of the trip arm is adjustable and the trip wedge is adjustable on the arm. You have to tinker the two until you get this. The trip arm is adjusted to push the mag up a min of 45 deg. , then trip the mag with the wedge just before TDC (I use 5 to 10 deg for low RPM engines). The points in the igniter should be closed until the trip opens them due to the over swing when it is tripped. The starting lever is to be in the running position while making the adjustments. When I had my engine running the timing would change due to a worn spot on the roller that caused the trip arm to ride higher then lower. Make sure your roller turns free and is not worn. Ron
 

Mitch Malcolm

Subscriber
First forget your volt meter its just screwing with things replace your mica in the ignitor and try it . them after its running try your meter to find out what the volt reading is on YOUR METER because without it being a constant spark they are all different...
 

Doug Tallman

Subscriber
It's been a while since I tinkered with one but I thought the webster manual said to take the springs and fingers off, spin it at 600 RPM, and you should get a reading in the 4-6v ac. I've never seen a spec on when it snaps or a recommendation to test it that way. I do second the new mica in the igniter. They build up with carbon which is a conductor. The compression causes the spark to go through it and ground out instead of jumping the points.
 

FunMobile

New member
Thanks for the guidance, everyone. Since this engine was operational at one point I'm going to assume it have changed and leave messing with the timing for last.

There is no paint or rust between the bracket and the magneto. After searching through a dozen or more archived threads I cannot find an explanation of where there mica washers/tubes actually are. It sounds like they're actually in the combustion chamber. Are they in this picture?

I do have good fuel draw and i have gotten this engine to fire the odd time or two, but never more than once at a time.
 

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ScooterBob

Subscriber
I see a homemade trip arm and ramp. Since you're getting a nice spark off the engine, I'd be looking close at the operation of your trip system to insure an appropriate mag wind up before trip off.
 

Merv C

Member
I am having the same issue with my Waterloo boy 2hp When I finished the restoration It ran really nice but now all I get out of it is one bang then nothing. then it floods. With the head off there is a good spark I think it is shorting out under compression and when flooded it is even worse. It possible to clean the mica washers?

Merv.
 

FunMobile

New member
ScooterBob, I hadn't checked this thread since my last post, but I was just coming back to ask if this mag push rod is homemade? Looks like you beat me to it.

I changed the Mica and still have great spark off the engine. At that point I started reading more deeply into how to set the timing on a webster. If I learned correctly the mag should trip 20-30 degrees before TDC while set to advance. Mine trips closer to 45 degrees before TDC in retard! See the second picture for where the mag trips in retard.

At that point I started to suspect the mag trip arm was homemade because the wedge will always lift the arm too early regardless of where the assembly is fixed to the exhaust push rod.
 

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Kevin O. Pulver

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I would recommend you get on eBay and buy doc shuster's Webster manual. It will tell you how to make sure everything is adjusted right once it's on the engine and will have more information than you ever wanted to know about your Webster. And if it needs service I can vouch for Mitch Malcolm at lightning Magneto doing fabulous work.
 
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