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MG MGB GT V8 Factory Originals Technical - Ice in carb

Went for a drive in my V8GT this morning in patchy fog with the temp. no where near freezing.
The car started to run very rough, had a job to keep her going. Limped back home took off the air filter to find the carb clogged with ice. The ice soon melted then she started and ran fine.
The carb is an Edelbrock 500 with K&N 2" filter with X stream Top.
Next time Ill warm up the engine and get everything cooking under the bonnet before I set off.
Mark Rawlins

I think you may have answered my problem, which is misfiring only when damp/wet, ideal icing conditions, ambient air temperature plays a part, but air temp. and pressure reduce with increase in air velocity i.e through a venturi? The K&N filters on the s.u set up do not receive any warm air until warmed up.Something else to check for thanks.
Nigel Griffiths

With standard SUs albeit with K&Ns I can't see into the carbs. But I have noticed many times that I need some choke for several miles and have to be very gentle with the throttle. But if I drive about a mile and switch off (paper shop) when I restart it doesn't need any choke and runs just fine. Whether this is icing or simply what heat is available after a mile warms the carbs when stationary I don't know.
Paul Hunt

I get ice in the SUs on long runs at constant motorway speeds - so much so that the butterflys are iced open - idle speed of 4000 rpm!

If I shut down for 4 or 5 mins then all is fine again........

I am thinking of routing some hot air off the exhaust manifolds to the K&Ns - a la factory air filter set up.
Chris Betson

I get the stuck throttle phenomenon on my 1800 B with K&Ns too, and I'm sure it is ice. Doesn't happen on dry days, no matter how cold.
Mike Howlett

Carburator icing is a common issue in aircraft engines while flying through fog (aka: clouds). The problem is caused by the rapid drop in temperature as air is sucked into the intake manifold due to the drop in pressure. When enough moisture is present, it can condense to water. When it's cool enough outside, it can form ice it the carb. The only solution is to raise the temperature of the carb or the air going into it. Perhaps closing some of the openings around the radiator to raise the engine compartment temp?
Chris Jones

I used to get 'throttle sticking' during warm-up on my HIFs until I soldered up the poppet valves.

Raise the engine compartment temp any more than it is!? Ye gods!
Paul Hunt

This thread was discussed between 16/02/2002 and 19/02/2002

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