Ok,
Lets talk emulsion tubes. I rather not discuss what the Weber books say regarding the Etubes, but rather discuss real world experience.
The books say not to change the etube unless on a dyno or have a very good feel for the way the car drives. I think those of us that have change these tubes know different.
When looking at this chart it says it goes from richer to leaner. It also indicates that the F7 is a richer tube than the rest.
What is kind of confusing (at least for me) is it say rich low. What is low RPM or vaccum?