[TR] zenith or su's ?

[Randall]

> 2. There is a behavioral change between the piston operating 
> in its range and topped out.  Once it is topped out the 
> mixture will get richer as the airflow increases, regardless 
> of how well or poorly it was set before.  If you use 
> full-throttle behavior as a data point you will be mislead by 
> that change.

Seems to me that this is exactly the same thing that happens when using too
small a fixed venturi carburetor.  Not only does the mixture go rich, but
the pressure drop across the carb increases, leading to less than maximum
power.  In general, if you are going to all the trouble of doing a carb swap
for improved performance, it's probably best to choose a carb large enough
for your application and thus avoid this situation.

Same thing applies (to a lesser extent) for using heavier springs.  You're
throwing WOT power away by reducing maximum airflow.

-- Randall