I just entered the data I collected today into a spreadsheet it is at
either
in excel format
http://red4est.red4est.com/lrc/blower/fuelair030216.xls
in staroffice format
http://red4est.red4est.com/lrc/blower/fuelair030216.sdc
There is a lot of "interpretation" going on. The readings off the O2
sensor would have very similar "shapes" running the same needle, but
the baseline or scaling seemed to vary run to run. I ended up with
much better qualitative data than quantitative.
On the "bottom" of the spreadsheet I have the profiles for the needles
in the order that they were tested:
stock BCF (book, and the section to be reprofiled as I measured it)
my reprofiling it from 0.500 to 1.000 inches, my second reprofile from
0.250 to 1.000 inches. The book measurements for a BBA needle, the
measurements that I took on a BBC that I had profiled, and the last
column is the customized profile of a BBA that I intend to try.
I want to keep the BBA "lean" at idle and at low power levels, then
bring it up to the profile of the BBC that I had reprofiled.
My heathkit CO meter has several scales on it. We recorded %combustion
efficiency as it was the finest scale. The scales translate roughly
to:
%CO %comb F/A ratio
effic
0 87.1 14.5
1 85.2 14.2
2 83.0 13.8
3 81.1 13.5
4 79.3 13.1
5 77.5 12.8
6 75.9 12.4
7 73.5 12.1
8 71.5 11.7
I did a fair amount of google research to try to find correlations
between O2 sensor voltage and F/A ratio. I've saved the various
documents that I found in the directory
http://www.red4est.com/lrc/blower
The primary data that I got was
1) confirmation that my first attempt at a custom needle was pretty
close under power, it seems to give a F/A ratio of about 13.2:1
2) A rough idea of where on the needle seems to equate to full
throttle at about 2000 RPM (about 3/4" down)
Another thing that I learned by watching the guages is that it really
does lean out when I go to full throttle from cruise. Even with really
thick oil in the carb, it still leans out.
To do this "right" it really does take a wide range O2 guage, however
I think that by having someone read the meters while I call out the
RPMs I can get a baseline that is close enough to save me quite a bit
of time on the dyno.
Larry
--
I've found something worse than oldies station that play the music I used to
listen to. Oldies stations that play the "new" music I used to complain about.
lrc@red4est.com http://www.red4est.com/lrc
/// or try http://www.team.net/cgi-bin/majorcool
/// Archives at http://www.team.net/archive
|