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Engine speeds up when one of the carbs is covered

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TulsaFred

TulsaFred

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What does it mean to you if the engine peeds up considerably whn I cover either SU with my hand?
Oddly it also speeds up if i take off the oil filler cap and over the opening.

Fred
 
It means the car is running richer, less air plus same gas = richer.
 
JPSmit said:
It means the car is running richer, less air plus same gas = richer.
Click to expand...

Hmm.. I would have said makes it run leaner, more air thru one carb, less overall gas- same volume of air being moved. Less gas because when you cover one carb you basically stop gas from running thru it. With no vacuum it will not lift the gas into the air stream.

I would think then that when running on both carbs they car may be a bit rich...

m
 
To me it seems like a vacuum leak. Extra air through an undiscovered leak= too much air to fuel. Cover a carb and decrease air to bring it back toward balance.
It's a dramatic effect though, it goes up by almost a thousand rpm.
Would seem like it would have to be a big vacuum leak because I can completely block one carb and get that amount of rpm increase.
Seems like that would be easy to spot.

Fred
 
Are there other symptoms?

m
 
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