I agree with Bill.  I think one reason Mazda wanted to make it difficult to
stick any other than the stock plug  is that some plug electrodes can reach
through into the combustion chamber and clip the apex seal as pointed out by
Paul Yaw.

Ed Anderson
----- Original Message -----
From: "Bill Dube" <bdube@al.noaa.gov>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Thursday, December 02, 2004 7:33 PM
Subject: [FlyRotary] Re: (unshrouded plug ?)required wrench


>
> >
> >If I end up using these plugs full time later, I will consider Lynn H's
> >suggestion to remove the eyebrows on the block, but really like to know
> >why Mazda went to the trouble of putting them on before grinding them
off.
>
>          Simply looking at the eyebrows, they seem to serve no purpose
> other than to make it impossible (or at least very difficult) to put in a
> 13/16" type spark plug. Perhaps this is their intended purpose. The Mazda
> folks don't want someone to put in the "wrong" spark plugs, perhaps.
>
>
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