[AT] Coating for small engine mag

[charlie hill]

Maybe not but I pulled my dad's A-C D-10 all over the yard one
day with a pickup truck trying to start it.  I had never had any
problem starting that tractor before.   My friend, who was driving
the truck, was a multi-craft mechanic in a local paper mill.
He pulled the plug wires out of the distributor cap.  There was
a fine white powdery residue on them.  Oxidation from the aluminum
in the cap I guess.  He wiped that off and put the wires back in.
We pulled the tractor about 2 feet and it fired.

Charlie

-----Original Message----- 
From: Rena Glover Goss
Sent: Friday, December 08, 2017 12:25 PM
To: Antique tractor email discussion group
Subject: Re: [AT] Coating for small engine mag

Umm.  Hey guys!  This has been an interesting thread, but I think there are 
a lot of "old wives tales" floating around on it.  Please learn the 
difference between a dielectric and an insulator, and that magnetism works 
differently than electricity.  You can channel the shape of a magnetic 
field, but there is no such thing as a magnetic insulator.  Just because red 
rust is non-magnetic does not keep a magneto from working, and polishing or 
painting the laminations of an electro-magnet will have no effect on its 
operation.


Larry
---- Ken Knierim <ken.knierim at gmail.com> wrote:
> A lot of modern electronics are potted with a very thin layer of plasma
> deposited PDMS. I would guess that in the case of the small engine 
> ignition
> parts they aren't coated as that material is a bear to make electrical
> contact through once it's been applied. It's tough to see too; it's very
> thin. It's largely replaced lacquer because of the environmental and
> handling issues except in potting of magnetics (they're still lacquer
> dipped in many cases).
>
> For me, I'd consider using some sort of lacquer, either dipped or sprayed
> on heavily to prevent moisture from getting into the coil. If it has a
> magnetic pickup side (next to a flywheel with a magnet for instance),
> you'll want a light coating of something non-conductive to keep the rust
> off the cores as rust degrades the magnetic operation. You also want to
> keep this layer thin as you need to have a rather specific gap between the
> magnet and the core laminations. The magnetic field drops off at the 
> square
> of the distance and a large gap can make it a bear to start.
>
> As far as the points are concerned, the newer (cheaper, "environmentally
> friendly") metals don't hold up well to corrosion and arcing. Arcing can 
> be
> mitigated by using the proper condenser (or an electronic ignition) as I
> remember this being a subject of my old 4-H Petroleum Power manuals (how
> the arc erodes the points could tell you if the condenser size was wrong
> and how to adjust for this).
> Since chromium and other materials formerly used in points manufacture 
> that
> resisted corrosion can be expensive and have toxic application phases 
> (like
> hexavalent chrome), manufacturers in this country can't use them. Silver 
> is
> good but very soft (and not cheap) and silver is one of the few metals
> that's also conductive in oxide form. (the other I can think of is ITO,
> indium tin oxide, which is also transparent and you're probably actually
> looking through it right now in your LCD computer screen.) Lots of 
> contacts
> (heavy AC contactors for example) use silver and other metals to provide
> good contact when exposed to air... these are usually costly and most
> ignition points are considered wear items (meaning "keep 'em cheap") so
> quality isn't what it used to be. So keeping them clean requires regular
> maintenance or a dry environment because anything that drives the water o
>
> Sorry for all the off-topic stuff this morning. Mind is wandering from 
> lack
> of coffee.. Hope some of this helps someone.
>
> Ken in AZ
>
>
> On Fri, Dec 8, 2017 at 4:41 AM, Henry Miller <hank at millerfarm.com> wrote:
>
> > I'm sure there is a reason, but I would guess cheap. These engines are
> > designed for machines that are expected to be replaced every 7 years or
> > so. If it runs that long they have their money and the customer thinks
> > it was reliable since it lasted that long. That it could last much
> > longer with just a little more cost is a bad thing.
> >
> > --
> >   Henry Miller
> >   hank at millerfarm.com
> >
> > On Thu, Dec 7, 2017, at 08:24 PM, John Hall wrote:
> > > I've can't ever recall encountering a flywheel magnet or a magnet 
> > > inside
> > > a magneto that was coated---must be a reason.
> > >
> > > John Hall
> > >
> > >
> > > On 12/7/2017 1:25 PM, Mike M wrote:
> > > > My wood splitter wouldn't start the other day, had plenty of gas, 
> > > > wet
> > > > plug, but weak spark. I suspected rust on the flywheel, so I tore it
> > > > apart and I was right. Cleaned it up, and now have a nice strong 
> > > > spark.
> > > > Question is, can I coat the mag and coil pickups with anything to
> > > > prevent the rust from re-occurring?
> > > >
> > > > Thanks,
> > > > Mike M
> > > >
> > > >
> > > > -
> > >
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