[AT] oil change

Larry D Goss rlgoss at evansville.net
Fri Dec 7 15:53:23 PST 2007 

Good article, Will.  Yes, it's the condensation of moisture inside the 
carburetor that does the damage.  By the time you see ice on the outside of 
the carburetor, things are really cold on the inside.

I'm reminded of a knuckle-biting situation I found myself in one night in 
Oklahoma.  A group of us (faculty) were teaching a night course in 
Bartlesville when an ice storm hit.  We headed to the airfield for a return 
flight to Stillwater only to find that there was nearly a quarter inch of 
ice on all the surfaces.  The pilot (Hoyt Walkup) had us pile in and he 
proceeded to race the plane (an ancient twin Beech) up and down the runway 
several times to no effect.  He would get up to takeoff speed and then shut 
down the engines in time to stop and turn around to go through the process 
once again.  Each time, he would shine his flashlight out the window and 
check the condition of the ice.  Finally, he said, "OK, I think we can make 
it on this trip."  And we headed down the airstrip one more time.  We were 
well beyond the point of no return when the ice suddenly turned to water and 
we were airborne.  I asked Hoyt why he didn't turn on the deicer?  The plane 
had been assembled out of three old planes and none of them had an operating 
deicer system.  So there was no system to turn on!  The heat buildup on the 
very front edge of the wings was enough to melt the ice at that point, and 
once the front edge was gone there was nothing to keep the remainder of the 
ice from peeling off the lift surfaces.  I suspect there were stains left in 
everybody's shorts that evening.

Larry

----- Original Message ----- 
From: "William Powell" <william.neff.powell at comcast.net>
To: "'Antique tractor email discussion group'" 
<at at lists.antique-tractor.com>
Sent: Friday, December 07, 2007 4:46 PM
Subject: Re: [AT] oil change


> Larry,
>
> No, that's not what I think I said.... At this point I can't be sure of
> anything... Sorry for the bad English, writing was never my strong
> subject....
>
> Here's what I found and I think they make a different point about energy
> consumption causing icing due to air pressure changes, not gasoline 
> crossing
> a phase barrier...:
> http://www.flycorvair.com/carbice.html
>
>
>
>
> "Ice can form on warm days. Anytime a gas expands from high pressure to 
> low
> it will consume energy from its environment. In this case, the gas is the
> air the engine is consuming and the pressure drop is from ambient to
> manifold  pressure, about 30"map to 12"map. The energy it consumes is any
> form of     available heat. Most of the heat comes out of the air. This
> temperature drop  is instantaneous and can easily be more than 40F. Shoot 
> a
> thermometer with a  CO2 extinguisher and learn."
>
> But, in section 5 they kind of make the point I was trying to make....
>
>    "Misted fuel is still a liquid, not a vapor. 100LL under these
>    conditions remains a mist until reaching the combustion chamber.
> Contrast
>    this with auto fuel, which by design will vaporize readily under these
>    circumstances. It is a fact of physics that when the fuel changes from 
> a
>
>    liquid mist to a gaseous vapor, it takes further heat from the
> surrounding
>    air. This is the cooling one feels when gas evaporates off the skin.
> This
>    additional temperature drop can produce icing when the same engine 
> under
>
>    identical circumstances would not ice with 100LL."
>
>
>
>
>
> I guess I did not really know what carb icing was, I just noticed the 
> frost
> on my WD when I plow snow, looks like it can effect the inside of the carb
> and be quite a problem on a plane....
>
>
> Regards,
>
> Will
>
> -----Original Message-----
> From: at-bounces at lists.antique-tractor.com
> [mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Larry D Goss
> Sent: Friday, December 07, 2007 5:11 PM
> To: Antique tractor email discussion group
> Subject: Re: [AT] oil change
>
> Carburetor icing is frozen gasoline?  Now that, I want to see.  That may 
> not
> be what you intended to say, but that's what I think I see.
>
> Larry
>
> ----- Original Message -----
> From: <william.neff.powell at comcast.net>
> To: "Antique tractor email discussion group" 
> <at at lists.antique-tractor.com>
> Sent: Friday, December 07, 2007 12:32 PM
> Subject: Re: [AT] oil change
>
>
>> >From little chemistry I had in college I always thought that the frost 
>> >on
>
>> >the carb was from the vaporization of the gasoline. I remember that when
>> >a liquid crosses the phase barrier to a gas it takes a lot of energy to
>> >cross... So, as with freon, when gas evaporates, heat energy is taken
>> >during the conversion which cools off the carb.
>>
>> Also, many old tractors do not have heat risers, so, the dense cold air
>> coming in does not  help the gas evaporate, so, you stall out unless you
>> force more fuel in by putting on the choke. Eventually the manifolds heat
>> up and your fine, slow speeds, low wind.. For an old tractor lover this 
>> is
>
>> a minor inconvenience, but probably unacceptable for most auto drivers
>> zooming down the road at 60 cooling off their manifolds.
>>
>> As far as the injectors, aren't most of them spraying in right at the
>> manifold near the head? That area probably heats up fast.
>>
>>
>>
>>
>>
>> -------------- Original message ----------------------
>> From: Ralph Goff <alfg at sasktel.net>
>>>
>>> ----- Original Message ----- 
>>> From: "Larry D Goss" <rlgoss at evansville.net>
>>> To: "Antique tractor email discussion group"
>>> <at at lists.antique-tractor.com>
>>> Sent: Friday, December 07, 2007 11:40 AM
>>> Subject: Re: [AT] oil change
>>>
>>>
>>> > Question of the day -- does carburetor icing occur on fuel injected
>>> > engines?
>>> > :-)
>>>
>>> Hi Larry
>>> If icing does occur in fuel injected engine I have never noticed it. My
>>> 97
>>> Blazer starts and runs smoother than any carbureted engine I have ever
>>> known. No stumbling or hesitation, no black smoke and stalling. I don't
>>> know
>>> how they do it but it works.
>>>
>>> Ralph in Sask.
>>>
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