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Re: general carb icing question

To: "Phil Bates" <>,
Subject: Re: general carb icing question
From: "Peter C." <>
Date: Fri, 22 Dec 2006 10:04:37 -0600
At 09:36 AM 12/22/2006, Phil Bates wrote:

>This is not an MG question, but I figured someone like Barney may have
>background knowledge on this.  I have a car with downdraft IDA weber carbs
>- one per cylinder - no chokes.  It's a little tough to start cold, but it
>works.  Anyhow, twice, my car has started to run crappy in the snow.  When
>I stopped driving I opened up the engine compartment to see that there was
>frost on the outside of carbs.  The first time it was one carb.  Today it
>was 3 of the 6 showing frost on the outside of the carb.  I haven't had
>the opportunity to look inside, but suspect its icing in there too.  What
>I don't know is this - what exactly causes icing??  I know it's the
>venturi effect, evaporation, and moisture - but is there a lean or rich
>condition that also increases the likelyhood of icing??  What is the
>effect of carb icing - do I end up with a chunk of Ice going in my
>intake?? Or maybe a jet blanking off due to ice and then a lean mixture??
>Phil Bates
         It actually goes rich.... same as choking.  Easily remedied 
with a bit of the foil hose run up from the exhaust manifold/header. 
It doesn't take much heat wafting into the air filter to eliminate 
the ice.  It may not happen on very cold days. It's been my 
experience that it is worse on those humid wet days with temps 
between 25 and 35F.

Peter C.

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