Michael,
As you gain in altitude, the air density decreases. There is just fewer
atoms of "air" (really 22% oxygen, 76% nitrogen, and other gases)
per cubic foot.
On an older carburetor vehicle, it doesn't compensate for the air
density. So you have the same amount of air getting mixed in a fixed
ratio with fuel. Result is a much richer mixture of fuel to air while in
the mile high city.
As you drop to sea level, the air density will increase. So the mixture
now has more "air" mixing with the fuel, giving a leaner mixture.
On the roadster, they do need to be leaned out at higher altitudes.
Ditto for later carburetor and early fuel injection. They had
"altitude compensation" devices. Basically an air bleed that worked
at lower levels, but would close at higher levels.
To meet EPA emissions, the later fuel injected cars started to change
how the measured air flowing into the engine, to get a better measurement
of the "mass" of the air. This will vary with altitude and temperature.
So most modern vehicle's run just fine in the mile high city, as they
do at sea level.
So your lady friend is correct, "the car didn't run the same". In the case
of a roadster, a tune up and readjusting the carb's is all that is needed.
This is one advantage of Solex carb's, you can easily change the jets
when up in the mountains.
For Mt. Shasta we do an annual "Run to the Rocks" on Sunday morning.
Start off in the town of Shasta, which I think is around 3,500 ft level.
Then up to Bonnie Flats, the upper parking lot is at 8,200 ft. You can
feel the difference in power as the cars head up the hill! Also fun is to
watch people get out and start running around on the years when we
still had snow up there. Impromptu snow ball fight, but I sat back
and waited for everyone to be gasping for air before charging with
snowballs! My son's soon learned you run out of breath sooner at that
elevation, too!
Cheers,
Tom Walter
Michael Tarelka wrote:
> To the Ring,
>
> What modifications would one make to a car driven in altitude, if it was
> moved to sea level? Carb Needles, Advance What?
>
> I told my lady friend about this cool car in the Mile High City and she
> proceeded to explain about her sister's car, who moved from Denver to
> L.A., Her sister said her car was never the same after the move and she
> had to get rid of it. This lady is terrific, but I don't think she
> likes Roadsters very much and she is no mechanic, but over the years
> I've discoverd the fair sex, has intuitive skill that can't be
> explained.
>
> What do you Datsooners think?
>
> Please advise.
>
> MT
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