When I had my Cessna 152 the A&P showed me how he
broke up the lead beehives which always formed on the
plugs of the o235.  It was simply an electric engraver
with sort of a fingered attachment.  Of course the
idea was to not touch the center insulator on the
plugs and fortunately enough the fingered attachment
curved conveniently around the center electrode.

After that, I did this every 25 hours rotating bottom
to top plugs.  I finally finished up with the blaster
material to finish the plug cleaning.  The plugs
always lasted at least 50 hours, though more typically
it was closer to 100 hours.

After looking at the plugs on the 13b the fingers
would easily break any deposits in the cross channels,
any deeper than that and it would be difficult to see
if you damaged the center electrode.

Something to consider...

-Scott



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