<VV> fuel/air mix theory

[chris czepyha]

> Did you disconnect the throttle link on the left side carb first? If
you are adjusting idle SPEED settings, they must be disconnected from
each other

I disconnected at the linkage on the left side.  Where it connects to the
cross shaft.  And twisted the swivel to make the readings closer to
matching.   Initially did not have it connected to the VA.   As they carb
came into sync, the idle speed reduced, and the difference in pressure
reduced.  I got overly excited (ran out of lunch time) and did not keep
going to see if I could get the gauge to not move at all.  
Will take for a drive to judge performance before making more
adjustments. 
Took it for a quick drive and it accelerated fine.  But only went a few
hundred yards.

In this order:
Disconnect throttle link on left side carb throttle arm.
Disconnect and plug vacuum advance hose.
Set idle mixture screws at two turns out from light seating.
Hookup idle dwell tach (0 to 1000 RPM setting). 
Start car and balance idle speed with idle speed screws on each carb
using Uni-syn or equal. Should be at an RPM you find comfortable. 
Play with idle mixture screws - 1/8 of a turn at a time - Adjust both
mixture screws  (left and right) the same amount. Try to get the highest
idle speed at the original speed screw settings. It will probably be
richer - IE the screw will be backed out from the initial setting. The
highest RPM means the mixture is optimal. If the RPM goes too high, you
may have to back off the Idle speed screws some to bring it down. (Not
likely) 
Once you have the idle speed and the mixtures where you want them, adjust
the left side throttle link to "just" slip into the throttle arm on the
carb. 
Check your vacuum advance hose. At this point you should not have any
vacuum going to the advance. If you do, something else is wrong. If you
do not - hook the hose back up to the distributor. You're done. - Seth
Emerson 

So the mix is kind of a curve?  Too low and the it will run slow because
its starving, too much and we get incomplete combustion and it bogs down.
Does this mix very upon use?
For instance normal street use, town speed limit is 35, which I strictly
obey.  Not looking to impress the kiddies, but need to be able to get
into traffic speed appropriately.  A couple of cruises require highway
driving.  Which I will let her loose if the wife is not in the car.

If I back it off from optimal, will that help mileage, but kill
performance?