"dual magneto"

[Kai Glaesner]

Hello,

reading the "no RPM drop..." thread gave rise to a question: what is the
benefit (if there is any) of the "dual magneto" (two magnetos in a single
housing) installation? Should these kind of installation be preferred, or
avoided (if there is a choice ;-)?

Thanks in advance for the answer..

Regards

Kai


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[Ron Natalie]

Kai Glaesner wrote:
> reading the "no RPM drop..." thread gave rise to a question: what is the
> benefit (if there is any) of the "dual magneto" (two magnetos in a single
> housing) installation? Should these kind of installation be preferred, or
> avoided (if there is a choice ;-)?
>

While the mechanical drive to a magento can fail, it's not a likely failure.
The main reason there are two magenetos is not so much that the magnetos
themselves fail often, but something in the entire ignition system connected
to that magneto fails. Since magneto's are pretty weak sparks, the usual
culprit is some fouling of the spark plug.

[Dan Thomas]

"Kai Glaesner" > wrote in message >...
> Hello,
>
> reading the "no RPM drop..." thread gave rise to a question: what is the
> benefit (if there is any) of the "dual magneto" (two magnetos in a single
> housing) installation? Should these kind of installation be preferred, or
> avoided (if there is a choice ;-)?
>
> Thanks in advance for the answer..
>
> Regards
>
> Kai

The dual mag leaves more room on the accessory case for other
stuff like vacuum and fuel pumps and so on. The drawbacks include more
difficult maintenance, as the two mags must be timed in accordance
with each other, and if the timing's off the mag has to come off and
be opened up to reset it. With two separate mags it's a matter of
loosening whichever mag is off and rotating it a bit to get it into
agreement with the other and with the engine. Further, these mags are
often on engines in tight compartments, surrounded by hoses and cables
and wires and sharp pointy things (like safety wire) and engine mount
tubes and other accessories and shoved up against the firewall, making
life unpleasant for the mechanic. We have one on a 182RG and I dislike
it intensely.
The other drawback is the single drive. There was an AD years
ago against the impulse drive springs in these things; they'd corrode
and fail, retarding the timing on both mags to TDC or worse, and the
power would drop to some useless value. Occasionally we hear of
another one quitting and remember that lots of owners are ignoring ADs
at their peril.

Dan

[Robert M. Gary]

"Kai Glaesner" > wrote in message >...
> Hello,
>
> reading the "no RPM drop..." thread gave rise to a question: what is the
> benefit (if there is any) of the "dual magneto" (two magnetos in a single
> housing) installation? Should these kind of installation be preferred, or
> avoided (if there is a choice ;-)?
>

They should be avoided. They have a nasty problem of falling off.
Mooneys and Arrows have had this problem. Most have since been change
over to two different mags. I think the benefits were easier
installation and less area to pressurize (for those mags that are
pressurized).

-Robert

[Ray Andraka]

another consideration is that the LASAR electronic ignition cannot be fitted to
engines with the two-in-one dual mag. It is only available for separate mags.
--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

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