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Re: general carb icing question

Subject: Re: general carb icing question
From: "Peter C." <>
Date: Fri, 22 Dec 2006 12:03:29 -0600
At 11:09 AM 12/22/2006, wrote:
>   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.
>Perhaps unwelcomed trivia, but in piston-power airplanes with carbs 
>you must apply carb heat whenever you significantly retard the 
>throttle.  The most dangerous time is, as Peter says, close to the 
>freezing mark and around visible moisture (i.e., clouds), but it can 
>happen on a clear day if the conditions are just right.  The venturi 
>causes evaporation, which is a cooling action, hence the ice 
>formation.  And, yes, as Peter says, your mixture gets too rich due 
>to partial blockage of the venturi.  While Peter's cure probably 
>would work fine to reduce/eliminate icing, as a rule otherwise you 
>don't want to pump heated air into the carb as the less-dense air 
>reduces power output.
>Jay Donoghue
Many cars had a flap on their air filter intake which would direct 
some warm exhaust manifold heat on cold days, and not on hot days. 
Frankly, it's pretty easy to fit the aluminum tubing when it's chilly 
out, and remove it when it isn't.


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