RE: Spark Plugs

["Kurt Musgrave" <rvar@domain.elided>]

Chuck,  you'll probably get several different ideas on this,  I'll throw in
my ideas.  The 303 Autolite plugs as far as I can remember are what are
listed for the IH engines.  They would be referred to as standard tip plugs.
The 86 plugs are extended tip.  Standard tip plugs will last longer in an
engine that is running extended periods such as most truck engines would.
The extended tip plugs will burn cleaner because they stick down into the
turbulence in the cylinder but they may not last as long in an engine that
runs long extended periods. This assumes similar heat ranges for each plug.
I don't know for sure but the 303 and 86 are probably the same heat range
just different tips.  Only way to know for sure would be to look at the heat
range charts in the Autolite book.
I remember the Ch**y pickups call for 26 Autolites and the same engine in
the C60's would call for 145's.  Same plug just different tip for assumed
different driving conditions.

Pick the type of plug that matches your driving conditions.

Kurt.