"Chris Newport" wrote in message
news:2363140.IDQUMr8mnb@callisto...

Sorry but you are wrong. For a given throttle opening the same volume
of less dense air passes through the carburettor venturi. The partial
vacuum created in the venturi is smaller, sucking less fuel into the
airstream and thus giving a weak mixture. Thus larger jets are
required at altitude to enrich the mixture.


Smaller jets are required as the altitude is increased.
Typically 1 size down for each 2000' in altitude.