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 Post subject: Carby Icing finds!
PostPosted: Sun Aug 13, 2006 10:21 pm 
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teh admin God
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Location: Smitho, Tassie
Well,
T'was a fair random thing.

I was in Launceston last night for a party, of which i am very tired from now as i did not sleep one bit, but at about 8:30 am whilst making my way back to Hobart, sitting on 110kays for at least 30 mintues already, just before the town of Campbell Town, i puy my foot down to speed up, and to my very much scaredness, as i released the foot off accelerator, the pedal did not, and proceeded to keep speeding me along at increasing speeds.
I was very scared, i could not lift the pedal back off the floor, so i turned off car straight away, and then jumped out and popped the bonnet to find the carby manifold on my twin su's the be covered in a thick layer ice that was as white as snow. It was such a pretty thing though. I then got my camera and took blurry photos, but then after a minute or 2 they all unfroze, with the top of the block being cold.
Then further down the road at Kempton about 9:30 i stopped at a shop to the very high idling of the pedal being stuck again, and the ice was about again.

So i now know that the things get ice all over them. And now i can safely say, that every single journey between Burnie and Hobart, i have had the same problems with the sticky throttle, though not this bad.

How does this work. I read that it can happen whenever it wants. And it would have happened whilst the temperature was at least 20 degrees as well.
But its just odd, as it will happen so often, in all weather and driving circumstances. 8)

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 Post subject:
PostPosted: Mon Aug 14, 2006 12:05 am 
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848cc
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Location: Mackay, QLD.
My mechanic builds light aircraft engines with SU carby. I'm not sure what they do but they've got some sort of vent setup on them that you open up if the carby starts to ice up. He was showing me the setup one day but I wasn't paying a lot of attention because I have a weber carb.

I don't think a weber would have this problem.

jacks.


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 Post subject:
PostPosted: Mon Aug 14, 2006 12:38 am 
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Location: Under the bonnet son!
Quote:
How does this work. I read that it can happen whenever it wants.



It's called the venturi effect. The resident physics gurus will tell you more, but I'm told it is to do with the drop in pressure from one side of the throttle butterfly to the other.

When you compress air quickly it gets hot yeah? Well all things being equal (or so Newton tells us) if you drop the pressure (opposite to compressing it) then the temperature will drop by the same amount. On one side of you carburettor inlet you have atmospheric pressure, on the other you have a vacuum when you are at idle or part throttle. This can be down to negative twenty PSI or so as the air crosses into this vacuum, it will drop in temperature dramatically.

You can stopicing by having a water heated manifold, quite easy to get and you can plumb it into the heater hose and turn it on or off with a heater tap.

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 Post subject:
PostPosted: Mon Aug 14, 2006 7:48 am 
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Yes a water heated manifold works. But as you have twins, there's not a lot you can do... maybe removing the heatshields (if fitted) will help.

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 Post subject:
PostPosted: Mon Aug 14, 2006 8:40 am 
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put a cople of cans of lager neerby so they can chill while you drive the WHEN you have finished your drive you have a couple of cold ones ready :wink:

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 Post subject:
PostPosted: Mon Aug 14, 2006 2:32 pm 
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I have to say, carb icing would have to be the easiest problem to fix on a mini!

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 Post subject: Ohhhhh???
PostPosted: Mon Aug 14, 2006 3:06 pm 
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[quote="1018cc"]I have to say, carb icing would have to be the easiest problem to fix on a mini![/quote]

Do tell 1018.... :lol:

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 Post subject:
PostPosted: Mon Aug 14, 2006 3:29 pm 
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1018cc wrote:
I have to say, carb icing would have to be the easiest problem to fix on a mini!


if you say by using a std manifold.....there will be much pokeage...

sounds like you had a bit of an experiance camel, perhaps a blanket would hepl your carbs, like your face hair keeps you warm!

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 Post subject:
PostPosted: Mon Aug 14, 2006 4:31 pm 
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1018cc wrote:
I have to say, carb icing would have to be the easiest problem to fix on a mini!


Pull over and wait till they become defrozen 8) :o

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 Post subject:
PostPosted: Mon Aug 14, 2006 5:54 pm 
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Welcome to the ice club Camel! I was wondering when you would turn up. :lol:
Because you were driving at a constant speed your carbs can ice up as long as the conditions are right. It is related to temperature and humidity.

What filters are you running? The standard Cooper S filter box has a long inlet pipe that picks up hot air off the exhaust to prevent ice in winter (you undo a clamp and shorten the pipe in summer) The bad news is that the S filter box is hard to get and even harder to get one that has not had the summer/ winter pipe cut off.

Try to avoid driving at constant speeds in winter! :wink:
You may find that when the throttle sticks and won't lift off, try hitting the pedal a little to break the ice. :wink: Just be ready with the key in case it does not work. :shock:
If you could get someone with a bit of talent to make up a warm air intake it would help.


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 Post subject:
PostPosted: Mon Aug 14, 2006 6:00 pm 
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Mick wrote:
It's called the venturi effect. The resident physics gurus will tell you more, but I'm told it is to do with the drop in pressure from one side of the throttle butterfly to the other. When you compress air quickly it gets hot yeah? (or so Newton tells us)


Good to see some 1 here quoting the man himself......Newton!

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 Post subject:
PostPosted: Mon Aug 14, 2006 7:07 pm 
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I have no experience with this but it sounds to me like you could spray something on the carbs/manifold that would stop ice forming... me thinks?
WD-40? Something that wont allow water to collect. (It is water/moisture icing up I imagine)

Wow, that would be scary... wild, but scary.

Peter.

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 Post subject:
PostPosted: Mon Aug 14, 2006 7:33 pm 
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It is the evaporation of petrol that causes the ice. (fuel injected cars do not ice up) What you need is warm air. :wink:

Cars that were sold in cold climates like Canada and the USA had electric carby warmers. One type was a heating element in the spacer between the carby and the manifold, the other type was a coil of hot wire around the carby piston chamber. These were thermostatically controlled. Neither system worked well. :lol:


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 Post subject:
PostPosted: Mon Aug 14, 2006 7:35 pm 
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Morris 1100 wrote:
. Neither system worked well. :lol:


the BMC story...

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 Post subject: Blank
PostPosted: Tue Aug 15, 2006 10:23 am 
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Have you tried blanking off the grill Camel :?:

Cheap fix and worth a try :idea:

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