Miata Mailing List: January 1994, Message #184
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   From: tkacik@adtaz.sps.mot.com (Thomas Tkacik)
Subject: Re: Splitfire
   Date: Fri, 21 Jan 1994 17:06:47 -0500


Andy Poling states:
>Let me re-iterate some warnings from an earlier date that Bosch Platinum
>plugs may not survive the Miata's funky one-coil-per-two-cylinders
>high-voltage wiring scheme since they may not tolerate sustained reversed
>polarity.  If the ignition system switches polarity every spark, they
>should be OK.  I dunno if it does this though - it is unlikely.

I don't think that it is a matter of the Platinum plugs surviving being in
a Miata.  It is more will they make any difference.  The platinum plating is
only on one terminal of the plug.  For the two plugs wired backwards, that
plating does no good (as it is on the wrong side), but they will not be
harmed.  They are more expensive, and there should not be any performance
or longevity gain.

The ignition system does not switch polarity every spark, it is
permanently wired one way.

Tom Tkacik
tkacik@adtaz.sps.mot.com