I suspect that the close proximity of the Classic rear exhaust headers
provides a lot of heat to the carb bodies. Thus comparisons with the XS
(where the pipes are routed further away from the carbs. and has no warm
air from the radiators) may not be relevant. Similarly the "s" engine is
said to be more prone to icing based on the assertion that it is drawing
more air and/or effects of the air hood.
If it worries you, then one option might be to hinge the ramp floor of
the NACA inlet duct thus enabling it ( with appropriate controls) to be
optionally closed off. In the closed position hot under-cowl air would be
drawn, returning you to the original pre-airbox situation.
This is just an idea and has not as far as I know been tried; the
under-cowl air might be warm enough to prevent ice in the first place, but
may not be warm enough to clear ice once it had formed during cold-air
operation.
Mike Dolphin's experience is worth a ton of theorising.
Duncan McFadyean
On Sunday, August 25, 2002 7:48 PM, Ian Mansfeld
[SMTP:ian_mansfeld@lineone.net] wrote:
> Does anyone know if making the plenum mod to take 'cold' air into a 912
classic mono with a 912 will increase the chances of carb icing? In other
words, do I need to consider the carb heating mod as well when
incorporating the plenum mod?
>
> Ian & BVVP.
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