Wow, one of the best tuning descriptions I have seen... nice job Keith. He is
right, high performance requires high effort and a desire to tinker.
Fortunately, I like to tinker! Maybe I should invest in a color tune...
Greg Burrows
-- Keith0alan@aol.com wrote:
In a message dated 5/18/2008 8:04:33 A.M. Pacific Daylight Time,
Geegc@aol.com writes:
I'm wondering if the front carburetor idle system is not supposed to work
and would appreciate hearing from any other owners of solex carburetors as
to
their experiences.
The front idle circuit is supposed to work.
I'm in Las Vegas so it's a little bit far to come by but here would be my
approach.
1) Figure out the leak and fix it. If it's something like the float valve
sticking open it will cause a world of problems.
2) Get out the Uni-Syn and make sure the air flow is balanced on all four
barrels at idle and high speed. If the air flow does not match between
barrels
on the came carb the either the throttle plates are bent or the throttle
shaft
is twisted.
3) Using a Color-tune (spark plug with a view) set each idle screw to set
the flame color to just on the blue side of the blue/yellow dividing point.
This
needs to be done at around 800 rpm. All four screws should be about 1 1/2
turns out.
4) At this point a gas analyzer/ oxygen sensor box should indicate about an
ideal mixture. Start slowly raising the engine speed. By around 1500 you are
likely to have gone lean or rich. Correct this by changing the idle/pilot
jets. This can also be done cylinder by cylinder with the Color-tune.
5) Go back to step three. Once you get to where the mixture stays flat
through 1500 then go in up to 2500. Once again it is likely to go lean or
rich.
Correct this with the main jets. This can be done cylinder by cylinder with
the
Color-tune or with the gas analyzer.
6) At this point most of the work is done. Drive the car and see if it
stumbles or bogs on acceleration. If so take a look at the accelerator pump
jets.
7) If it's stumbly/ lean or rich at high speed full throttle driving then
the air corrector jets or emulsion tubes need adjusted.
The obvious question is "Can't someone just tell me to put in X pilots, Y
mains, Z air corrector, Q accelerator pump jets, etc, etc?". The short answer
is
no. These carbs are sensitive to the exact engine they are on and must be
tuned to that engine. If you set your's up like those on another car you
should
be close but it's just a starting point.
Also, it's entirely likely that you will find that three cylinders are fine
with one jet size and the fourth is rich or lean. Yes this happens. Jet each
cylinder to what it wants to run properly.
The initial setup is very time consuming but once done future fine tuning
goes much faster.
keith "I love my SUs" williams
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