[SEL] Recharging of Maytag coils

Wed Jun 10 07:30:19 PDT 2009

Yeah, long time.
Well, I missed the MN meet - Mike was tied up moving his sister back to
Iowa so he didn't go, and I was busy working on my Javelin and other
projects.
Then Waukee came up and I didn't make that either! Just too much going on
this year.
I would hope it was better- last year it was really really down - of
course the high fuel prices helped do that.
Mike was fine last I spoke with him - been a few weeks. He keeps busy, too
- still get email from him every few days. Him and his corny jokes!

HOPEFULLY, next year I'll be back into the engines, this year, it's the
year of the cars........Major restoration of the rear suspension and
undercarriage on the Jav - attention to detail like proper bolt finish,
etc.
Some have compared my differential restoration to the Ashmeade MD Javelin.
(google that one)

Bill

> Hi Bill,
>   Long Time no hear. How was Waukee this year? I hear things were
> some better then last. Sure missed going out.
>   Hows Mike B  haven't heard from him in even longer. Mark
>
> At 09:26 PM 6/8/2009, you wrote:
>>Yes, I was trained by Sun on the use of he scope, own a scope now, and
>> got
>>my first job by showing the service manager what was wrong with the Ford
>> he
>>ws working on.
>>You can see it all in the scope pattern...... And tell a LOT about an
>>engine, even mechanically, if you can read the scope.
>>The full operating of the system would take pages............
>>
>>I've still got all my Sun training guides downstairs......... Pages and
>>pages.
>>
>>-----Original Message-----
>>From: sel-bounces at lists.stationary-engine.com
>>[mailto:sel-bounces at lists.stationary-engine.com] On Behalf Of Elden
>> DuRand
>>Sent: Monday, June 08, 2009 6:48 PM
>>To: The SEL email discussion list
>>Subject: Re: [SEL] Recharging of Maytag coils
>>
>>Jerry & Bill:
>>
>>A couple of years ago, I did a study of point/coil/condenser (battery or
>>mag) and ignitor ignition electrics.
>>
>>The condenser is, in fact, needed in order to produce a "hot" spark at
>> the
>>plug.  As a side effect, it also supresses arcing at the points.
>>
>>What you have with this type of ignition is a parallel resonant L/C
>> circuit.
>>The "L" is the inductance of the primary of the coil plus the reflected
>>inductance of the secondary of the coil.  The "C" is the capacitance of
>> the
>>condenser.
>>
>>What happens is that when the points are closed, there is a magnetic
>> field
>>produced by the primary in the core of the coil.  At this time, the
>>condenser does not exist in the circuit, being short-circuited by the
>>points.
>>
>>The fun begins when the points open.  As soon as the points open, the
>> field
>>of the coil begins to collapse, inducing a voltage across the condenser
>>which is now in the circuit.  The rate at which the voltage rises is
>>dependent upon the capacity of the condenser and the inductance of the
>> coil.
>>Once the coil's field has collapsed completely (and made one spark at the
>>plug), the condenser is charged up and has nowhere else to discharge
>> itself
>>but back into the primary of the coil, which it does, causing the
>> magnetic
>>field to build back up in the coil (albeit at a lower voltage|).  When
>> the
>>condenser has discharged itself, the field of the coil again collapses
>>(making another, weaker, spark) and charges the condenser again.  This
>> goes
>>on for several cycles and is called a "damped oscillation".
>>
>>The reason the points burn if you don't have a condenser across them is
>> that
>>the voltage rises faster than the points can open and a series of small
>> arcs
>>occur at the points as they relatively slowly open, adding up to a big
>>heating event.
>>
>>There is actually a damped oscillation in the coil even without the
>>condenser.  This is caused by the distributed capacitance of the coil and
>>wiring.  The frequency of this oscillation is very high and the coil, as
>>designed, is very inefficient at producing a high secondary voltage at
>> this
>>frequency.
>>
>>If you want to see oscilloscope pictures of what happens in a
>>point/coil/condenser, go to my web page (below my signature) then go to
>>"Otherstuff" and pick your subject.
>>
>>Oh, yes.  You can get very scientific about the value of the condenser
>> used
>>but most of the coils aren't very picky about just what resonant
>> frequency
>>they resonate at.  As long as the value is between 0.15 microfarad and
>> 0.47
>>microfarad, you should be okay.  If you get a non-automotive condenser,
>> get
>>a film type (NOT ELECTROLYTIC!) capacitor rated at 630 Volts DC and you
>> will
>>be fine.
>>
>>Please note that this is just an audit class.  No quizzes will be given.
>>
>>Take care - Elden
>>http://www.oldengine.org/members/durand
>>
>> > -----Original Message-----
>> > From: sel-bounces at lists.stationary-engine.com
>> > [mailto:sel-bounces at lists.stationary-engine.com]On
>> >  Behalf Of
>> > bill at antique-engines.com
>> > Sent: Monday, June 08, 2009 02:14 PM
>> > To: The SEL email discussion list
>> > Subject: Re: [SEL] Recharging of Maytag coils
>> >
>> >
>> > Having a degree in automotive technology, earned when points were
>> > still in use to some degree, here's why I state that it MAY, mind you
>> > MAY not start and/or run, or run properly:
>> >
>> > When the points open, the sudden loss of primary current causes a
>> > quickly collapsing magnetic field in the coil which induces a larger
>> > voltage in the secondary windings. The voltage traveling through the
>> > secondary winding in turn induces a current flow, in reverse, in the
>> > primary circuit
>> > - enough to cause the points to arc.
>> > This "back emf" is due to the design of the ignition coil and its
>> > inherent inductance.  This feedback of electrical energy causes a
>> > spark to occur at the points that pits and erodes the contact
>> > surfaces.  To suppress this energy, a condenser is used.  It acts like
>> > a shock absorber (absorbing the back emf), ** and in so doing it helps
>> > to interrupt the primary current as quickly as possible when the
>> > points open.
>> > Without the condenser, the back emf would form an arc across the
>> > points as they separate, ** slowing the collapse of the coil's field,
>> > thus delaying and thereby reducing the voltage rise in the secondary
>> > coil winding - ~possibly~ reducing it enough to cause it to not span
>> > the plugs gap.  The condenser suppresses most, but not all of the back
>> > emf. So points still burn or erode.
>> >
>> > Bill
>> >
>> > > It should start and run without the condenser
>> > but only till the
>> > > points burn which can be fairly quickly. The
>> > condenser has little to
>> > > do with the actual generation of spark, more to
>> > do with the
>> > > protection of the points from arching and
>> > burning quickly. If you try
>> > > it without a condenser gap the points a bit
>> > wider then the spec .020
>> > > to get a clean break or so that the arc flame
>> > between the points does
>> > > quit due to width of gap.        Mark
>>
>>
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>
>
> Mark Shulaw
> 454 Co. Rd. 33
> Bluffton, OH. 45817
> USA
>
> Frappi at wcoil.com / 419.358.5206  Home / 419.516.2996 Ver. Cell.
> Hobby Collector and Dealer in Maytag Multi-Motor Engine parts.
> VISIT the Maytag Collectors Club at  www.Maytagclub.com
>
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