<VV> Leaning Out the Midrange

[Frank F Parker]

> 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.

Depends on which device Ray sold you. Sounds like it is a led display that 
reads out the std 1-4 wire narrow band sensor. You can say it is rich but 
it is hard to really pinpoint anywhere in the 11-12 range. I am sure it is 
quie rich and you are on the right trail in buying a broadband meter. 
Highly suggest the Innovate metercause it is accurate and can log 5 other
channels including rpm with an accessory. I loaned mine to Ray and he 
tested the turbo Corsa I bought from him. It had a YH that just would not 
work after being rebuilt a number of times. The Innovate proved that and 
he put on a loaner for me to use till my recent disassembly to do a port
fuel injection setup. Ray is now an Innovate dealer and can supply you and
give great support in your testing. By logging wb O2 and rpm and possibly 
map by using a cheap GM map sensor availble in any junk yard for a few $$, 
you can log up to 44 min of data, then be able to download at your liesure
and see accurate data and see what rpm and vacuum at which fuel 
transistions occur.

regards,

frank