[alfa] Spark plugs and burned valves

[John Brase <jbrase@xxxxxxxxxxx>]

In the 70's, when I was stationed in Germany, a friend drove his 1300 GT 
Jr. to Italy and when he got there he had burned an exhaust valve so 
badly he had to have fixed there.  Then he drove it back to Germany and 
by the time he got back it ran very badly.  We pulled the head and found 
two exhaust valves badly burned, to the point where they each had a big 
"C" shaped piece melted out of the valve faces.  The melted spots were 
the spots nearest the plugs.  After much head scratching I figured out 
that the Champion plugs he had put in were way too hot.  (Turns out the 
cross reference chart was wrong.)  At sustained autobahn speeds the hot 
plugs appeared to be igniting the fuel as it entered the cylinder and 
essentially creating a blow torch which was pointed right at the exhaust 
valves.  So, too hot plugs can indeed burn valves under the right (or 
wrong) circumstances.  I'm sure the hemi design played a part in this 
episode as well.  Interestingly, his pistons were fine.  After he went 
back to Lodge plugs the problem never reappeared.

John
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