Hi barit1,
I suppose you're right there. But isn't the pressure drop across the venturi minor compared to the factors you're neglecting? The venturi is designed to be as close to lossless as possible. You can see that by the fact that every surface is smooth and rounded, with no sharp corners.
I suppose if I were to rank causes of loss of manifold pressure in a typical aero engine, I would say throttle (except when open!), then air filter, then ducting & corners, then carburettor venturi. As I'm not an engineer I could stand to be corrected though.
The main problem with talking about the pressure drop across the venturi from my point of view, is that it tends to confuse the inexperienced. There is a big difference between the pressure drop within a venturi and across a venturi - one is Bernoulli, which is where novicef got confused, and the other is a loss of energy caused by turbulence and the airflow being choked, which is definitely not Bernoulli.
Hope this clarifies my posts,
O8