I think this is the spec on ventury vacuum (V V) at max specified CFM.  Performance carbs (generally 4 barrels) are designed with about 1/2 the ventury drop as "grocery getter" carb designs.  The less the V V, the better WOT performance (more MAP) but the harder it is to design due to the smaller signal.  10" H2O is a pretty small signal for MAX CFM.

 

BTW, This is unrelated to throat size.

 

Tracy Crook

 

On 8/23/07, George Lendich <lendich@optusnet.com.au> wrote:

Ed, Lynn, Bill or anyone.

I'm trying to figure out how to extrapolate various air flow figures which have different vacuum testing parameters such as those with 10" of water verses those with 12" of water and 20.4" of water. I don't know where the 20.4" of water comes from, but apparently it does exist.

I assume there is some calculation which can be applied?

I'm only concerned with extrapolating from one ( known value like 10") to another ( like 12") - for comparison purposes.

George ( down under)