<VV> Leaning Out the Midrange...Continued

[Mikeamauro at aol.com]

Greetings and salutations:
I've been on a mission to improve the efficiency of my 67,110 coupe  (history 
detailed below in previous post). The vehicle gets  consistently poor fuel 
mileage: around 16 mpg, combined Hwy/City.Since the  last post, at cursing speed 
(55mph & steady) A/F ratio of the  dual exhaust vehicle has been tested with 
an Innovate brand broad band device.  The results show the following A/F 
results: Left Bank = 12.8, Right Bank = 12.1.  Both readings are a few clicks rich 
from the ideal stoichiometric fuel mixture  of 14.7. As the main jets are 
already .049s, and the main jet size has little  (if any) effect on midrange A/F 
ratio, my next step is to open up the air bleeds  on top of the venturi 
clusters. The bleeds will be adjusted  upwards using numbered drill bits, and will be 
opened up just one or two  numbers at a time (between retesting A/F ratio).
 
Observations or suggestions?
 
Mike Mauro

FROM  PREVIOUS POST: I've installed Ray Sedman's F/A O2 sensor readout system 
on  my 67 110 coupe. Readings obtained indicate the F/A mixture is  
consistently rich (11-to-12-to-1) in the cruising range. I've gone as lean as  I dare 
with the main jets (.049s), but jetting does not appear to  significantly 
affect midrange mixture. The purpose of my work is to improve  fuel economy (and 
yes, all is well--mechanically--with the engine). My next  step is to purchase a 
broadband F/A diagnostics device (likely with additional  RPM input) and 
begin experimenting with the internal working of the carbs in  an effort to lean 
out the midrange. QUESTION: has anyone out there already  ventured down this 
path? What area in the stock carbs is the most likely place  to start in working 
on the midrange F/A mixture?
Thanks in advance for any information provided. 
 
Mike Mauro
67 110 PG Coupe, with Factory Air