Tim---I don't know if I can help or not, but let's go over a few
things..First, you paid $ to have an air/fuel monitor. Situations such
as you described are exactly why they are sold to after market users.
Get the blasted thing connected, for starters.
Having only one sensor sending info about three carburetor mixes won't
make it easy to sort out what it's telling the monitor. As you must
know, the exhaust could now be a mixture of two rich carbs and one lean
one, for example. You'll need to look at your sparkplugs to make sure of
even coloring. Anytime one goes it alone when modifying an engine can
find themselves wondering if the did the right thing! OK, enough with
the philosophy.
With the monitor hooked up and the new ground wire connection, (or at
least with no accessories on,) start backing off on each carb needle
raising/lowering piston. If necessary to get a reference point, see how
many 1/4 turns it takes to bottom out each carb screw by turning it
clockwise. (You'll feel the screw resist further turning.) This will
make the running rich, but will tell you at least that ALL the carbs are
set the same way. Your monitor should show all the green lights glowing,
or a stoich of about 12:1 + .
If you're more comfortable in doing so, take the four screws off the top
of each carb and lift out the piston. You'll be able to see the needle
go up into the piston as you screw the adjustment clock-wise.
Otherwise, do it with the top of the carb on.
With the air/fuel monitor showing a very rich condition, (all LED's
glowing) now you can start backing OFF on each carb, in turn, one-half
of a turn each. (Note the wrench angle before starting these turns, and
do each one the same.) Blip the throttle, if necessary to keep the
engine happy, or even let it run at a fast idle for15 seconds. Watch the
monitor as you make these adjustments. As you lean out each carb,
eventually by making only 1/8 turn adjustments, you will start to see
the "rich" lights start to disappear. Take this leaning out process to
where the engine isn't happy with it's meager diet anymore. Increase the
idle speeds if you have to, to keep it running. If you can get the
engine to idle without the green lights glowing, at idle, that's all you
can do with the carbs and the needles provided.
I, for one, am not entirely convinced that a "big" cam must run rich.
More than likely, it just doesn't run efficiently, especially at idle
and shows up as unburned hydrocarbons, and picked up by the 02 sensor.
Tim, this may be boring the socks off those who have no interest in
trip-carbs, or air/fuel monitors. Try the above, and let us know if you
feel this is on the right track. You know you can write me directly, as
there's a ton of info on this that isn't prudent to write at one
sitting, or using this forum.
Dick T.
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