"Kai Glaesner" wrote in message . com...
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