<VV> ambient???????

[Mark Durham]

A temp of 30 degrees F is a bone chilling day down next to the
seashore in high humidity, but may be a short sleeve shirt day where
the air is dry. So, those conditions are noticeable to us and to the
engine, But the choke coil does not feel a difference. It only feels
30 degrees. So, ambient air temp is the temp where ever you are, or in
this case, the discussion is on carburation and choke adjustment, so
ambient is the air around the choke coil.

When the air is blown down through the cylinder and head fins, the
engine will cool at different rates for humid air versus dry air,
because the moisture adds a cooling element all its own. Not sure we
would notice the difference, however.

The choke pull-offs are a coil spring affair that get tighter when
cold, and opens up as it  warms up. On a cold day, when you press the
gas pedal the first time, the chokes close. For any particular
setting, they will close tighter (richer mixture) when cold, and less
tight when warmer.

You adjust the chokes so when you start the engine, it runs. If it
puffs black smoke for a few seconds, no big deal. But if it continues
to do so after thirty seconds or so, you need to adjust the choke rods
a bit shorter. If the engine stalls when started, then you need to
adjust the choke rods a bit longer to increase spring tension and keep
the choke plates more closed with air flowing past them.

I used to reset choke adjustments two or three times a year when the
Corvair was a daily driver. But, I have temp swings of +95F to -20F to
deal with each season. Hope this helps.
Mark Durham



On Sat, Jan 15, 2011 at 10:54 PM, J R Read <hmlinc at sbcglobal.net> wrote:
> The air in your garage, carport, driveway - or wherever else it may be
> parked long enough to cool down to "ambient".  Once running, the ambient
> temp has little effect on the choke coils since they heat up right along
> with the engine.  When cold outside, the engine starts at that colder temp
> it takes a little longer for the engine to get warm enough for the chokes to
> open up.
>
> Later, JR
>
>