<VV> Carb Rebuilding (added...Fuel Efficiency)

[Jim Burkhard]

Mike -

Excellent commentary!  It's good to see somebody making good use of 
modern technology to improve carb tuning techniques.  The Innovate 
products are good ones at a great price -- we even use them at work 
for non-critical development.  They are every bit the equal of the lab 
grade wide range systems offered by ETAS and NTK, with the exception 
of a very *slightly* slower response time.  The difference in response 
time might matter for OEM direct injection, but not at all for carbs 
or even aftermarket tuning.  Keep posting more details on what you 
learn re the carb tuning -- the wide band sensors are much better 
tools than were available OEM engineers in the 1960s.  Watching how 
the carbs perform during transient maneuvers is of particular interest 
to me.

Jim Burkhard

Mikeamauro at aol.com wrote:
>  
> "...The lower the float level, the leaner the high speed mix. Do not  apply 
> pressure to the needle in the seat when doing this  adjustment..."
> 
>  
> Actually, checking using wide-band instruments, I've found float  level comes 
> into play a lot earlier: from just off idle transition, and  throughout the 
> mid-range. Nearing WOT, I'm sure the fuel level pays a part, but  with fuel 
> enrichment circuit equipped carbs, once enrichment kicks in, it's a  little more 
> difficult to separate out what can be attributed to float  level, and what is 
> enrichment. By tweaking (lowering) the float levels,  I've been able to 
> maintain (at around town & cruse speeds), between 14  to 15 A-F ratio. The car I've 
> done this with is a 110 with PG and dual  exhausts. I've installed in-cockpit, 
> dual wide band digital instruments (by  Innovate), so I can see what is 
> happening under all conditions,  side-to-side. Before float tweaking, even after 
> reducing jet sizes to  under OEM speck, I could never get the system to run 
> leaner than about  13.5. This speaks to the fact that jet size is most influential 
> under WOT  conditions. Another thing I'm trying, to lean things up a bit, is 
> to make  the enrichment needles a little heaver: I've filled the depression in 
> the tops  of the needles 1/2 way with soft solder. OBTW: this and all my 
> other  Corvairs are Safeguard-equipped. If you do not have a Safeguard, or Clark's 
>  knock sensing device, be extremely careful in your leaning attempts.
>  
> 
> Mike Mauro