> No, simply a question to Randall Young about this thread. Is it
> common (i.e. normal) to have the air flow synched at idle but
> different at various rpm's, and if it is considered abnormal what
> might this indicate and what should be done about it?
My observation is that following the book procedure on the H6 setup original
to TR3/A/B/early 4 *will* result in a measurable mis-match in flows off
idle. I can't say with any certainty that it is abnormal, or even that
there is any real advantage to eliminating it, but doing so does seem to
make the engine run slightly smoother at low rpm/throttle.
The problem is that the book says to synchronize air flows using the stop
screws, and then tighten the clamp connecting the two throttle shafts
together. But since the pedal acts directly on the front throttle shaft,
and there is a spring on the rear throttle shaft, the coupling distorts
slightly against the spring tension and the rear throttle does not open at
the same time as the front one. My approach is to synchronize the air flows
off-idle first, then tighten the clamp and reset the idle stop screws to
keep them synchronized at idle (in effect keeping tension on the flex
coupling).
The 'synchronizer' in the tool kit basically gives a visual indication of
relative piston movement (without the damper) between the two carbs, which
is a sensitive indicator of air flow. Since it is "real time", you can
compare flows as the pistons move. You would need two Uni-syns to do the
same thing (and even then there is a problem, since the Uni-syn only gives a
good reading over a fairly narrow range of air flow).
Randall
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