<VV> Carb base leak

[Stephen Upham]

<snip>
Don't forget all 64 and up carbs have a built in vacuum leak at the  
base of the carb on purpose.

I received this reply to my carb base leak problem.  I admit that I  
don't know a lot ...yet, but I've never heard this before.  If it's  
true, then perhaps the 100-200 rpm increase that I see when I spray  
carb cleaner at the base of the carbs is "normal".

As to other possibilities:
The throttle rods can be eliminated as a source as these are newly  
rebuilt carbs by a respected carb rebuilder and were checked for fit  
by club members. The crossover tube has been eliminated as a source  
because the rubber connections are brand new and I have them  
connected with hose clamps!  Over kill, I know - but I attached them  
that way in order to eliminate that source as a reason why my PG is  
kicking when coming to a slow stop. In addition, spraying carb  
cleaner on them or the junction to the transmission has no effect on  
the rpm.

I really want to eliminate all possibilities before removing the  
carbs and doing any filing on the bottoms.

Anything else I'm overlooking?

Stephen U