<VV> Carb base leak

[Frank DuVal]

I thought about the idle vent valve when Steve first mentioned spraying 
the base of the carb. But I thought it shouldn't have that great an 
effect, but maybe it does.

The idle vent valve (aka vapor vent) is not a vacuum leak. It vents the 
area above the throttle plate only at idle, when the throttle plate is 
closed. If the throttle plate is slightly open, then spraying something 
at the base of the carb will get into the venturi area. OK, so it is a 
controlled vacuum leak.

This vent was added in 1964 to aid in venting the carb venturi to avoid 
hot start issues. Fuel percolation after shut down caused vapor to build 
up in the venturi. Then you had a very rich mixture if you restarted soon.

So what Steve is seeing may be normal.

Bob may add corrections.

Frank DuVal

ScottyGrover at aol.com wrote:

> 
>In a message dated 6/1/09 2:56:05 P.M. Pacific Daylight Time,  
>contactsmu at sbcglobal.net writes:
>
>Don't  forget all 64 and up carbs have a built in vacuum leak at the  
>base  of the carb on purpose.
>
>
>
>This I didn't know; please tell me why a vacuum leak was engineered into  
>the carb? It seems like a loss on control.
> 
>Scotty from Hollyweird
> 
> 
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>  
>