Well...Brad...
The air density difference in 200-400'
above wherever you are altitude-wise isn't hardly even measureable.
The book doesn't recommend going to
a leaner needle in terms of less dense
air until you exceed at least 3,000 feet
above sea level, a weaker carb. setting
being all that is necessary using the "standard needle"
At altitudes above this point it becomes
a toss-up between running the "standard"
needle "leaned out" or the recommended (for the specific application)
"weak" one.
At 5,000'above sea level (density altitude)
you definitely should be running the
recommended weak needle, though you
could get by going even leaner with the
"standard" needle which becomes progressively less of a good choice
though, by the time you reach density
altitudes of 5,000 feet above sea level.
Density altitude is pressure altitude corrected for non-standard
temperature.
You'd be effectively at a higher altitude
(less dense air) on a hotter rather than
cooler day at the same pressure altitude
cool air being more dense in "air" molecules than it's warmer
counterpart.
Humidity is not factored in but the
more humidiy (water molecules) in any given parcel of air, the less room
there is
within that parcel for "air". The engine
"feels" this as in less or more dense
in air molecules. To offset this is the
"cooling effect" of relatively more humid
than less humid air.
And...now that I've told you all this...I
will have to kill you. You too, Pat! <VBG>
Cap'n. Bob
'60 :{)
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