Rick:

Certainly true.

I must have been thinking mixture effects.  My mistake.  Don't know what the heck I was thinking...  apologies.  Thanks for the catch.

Walter


On Dec 26, 2005, at 11:47 AM, Marvin Kaye wrote:

Posted for Rick titsworth <rtitsworth@mindspring.com>:

 Can you further explain or site a known/scientific reference source for your
statement below?
  "High altitudes increase the voltage required to jump the gap on the plug"
  Commonly understood engineering/physics is that increases in air
pressure/density impeeds a spark.  Thus, as air pressure/density is reduced
(increased altitude) a spark will normally be EASIER to initiate.
  Reference: "...The Physics Fact Book" @
http://hypertextbook.com/facts/2000/AliceHong.shtml - "The dielectric strength
of air is approximately 3 kV/mm. Its exact value varies with the shape and
size of the electrodes and increases with the pressure of the air...".
 Additional factual references are cited at the link above.
  Additonally/empirically, I've seen weak coils that would "spark" a plug out
of an engine cylinder, but that would not create a spark under the pressurized
conditions inside a "compressed" cylinder.  e.g.  high pressure increases the
voltage required to create a spark.
  Why would High altitudes (low pressure) require MORE voltage???
   Rick
 - always open to learning something new, if true.

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