That's a really great question James!
I'm listening to the differential sound of air being sucked into each
carburettor....
it's a really old school method of shop tuning multiple throat setups.
It's s bit like music, both, or all, because v12 dragons do exist, seperate
throats
need to have the same tone.
There are various meters on the market that can also be used that make the whole
exercise pretty fool proof, but when you come up against 8 and 12 throat setups
i find the listening tube method is much quicker as there is no setup time
required.
Along with remaining attentive not to walk into the spinning propeller I found
the air of the prop wash a bit of a challenge to work with so i used the
rearward
ear to listen, and chose to lower the faster throat than speed up the slower
one.
(I'm also periodically lifting each carburettor piston about half way to
determine
which carburettor is running rich or lean than the other; and thats a whole
seperate but related procedure)
Sometimes you may also hear crackly clicking or popping in a carburettor throat;
this is indicative of un-atomised fuel entering the throat due to float levels
being too high and it gets more prevalent as flooding begins.
The better the balance, mixtures included, the slower the engine can be idled
smoothly;
the 80hp could probably happily achieve 300rpm if not for the required
cdi exciter speed and self destructive gearbox backlash. The 100hp would likely
start hunting at about 900rpm due to valve timing.
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http://forums.matronics.com/viewtopic.php?p=507424#507424
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