Chris, the setup i just bought the bits off fleabay and made one; the case is 3D
printed in PETG with two velcro securing straps and the T'piece for the sensor
i had to custom drill and tap to suit... i can make more units ready to use
out of the box, and they would be around $600 Aud plus postage; the unit can
be used in the cockpit during flight testing for specific altitudes tests also
and has self contained battery power or plug into 12v supply and recharging.
The tail pipe fitting length negates proximity contamination to external
atmospheric
air and fits 36mm - 40mm tail pipe sizes with provision for safety cable
attachment should the T'piece depart during flight.
Balancing carbis at 3500/4000 etc is fine however its a lazy way of going about
it and will only offer Intermediate range tuning, so that would be needle height
adjustment only. Adjusting mixtures and butterflies for smooth idle are best
achieved at the lowest possible rpm (operational idle rpm is set afterward);
have had triple SU Aston Martin DB3's happily idling at 150rpm while setting
mixtures... SU and Stromberg CV tuning method would be the most appropriate
applied
approach for Bing64 series. The only other point to note is symmetry of
needle height position; if they are not the same height on each carbi and your
tuning is complete then you have an issue remaining either an air leak, high
or low float level, or unbalanced butterfly valves; take everything back to
default
and start again to find the reason for rich or lean side.
Seasonal changes in specific gravity of fuels will alter the tuning slightly on
cold startups as it affects the barometric vaporisation point of the fuel (for
Darwinian safety reasons modern pump gas is designed not to vaporise, its
designed
to be sprayed and atomised at high pressure). Avgas however will readily
vaporise and has a specific barometric vaporisation point that must be
deliverable
and adhered to to prevent vapor locking up to a specified pressure and
temperature.
Bud might offer a better explanation as i never cease to expect everybody to
just
automatically know all this stuff!
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