----- Original Message -----
From: "Fred Fillinger" <fillinger@ameritech.net>
Subject: Re: Carb. balancing
> Roger Anderson wrote:
> >
> > I have an old ASI, and I was wondering if this could be used to
adjust carburettor balance by repositioning the pointer to a mid-position
and then connecting it in place of the transfer tube - pitot to one
carburettor and static to the other. After all it is only equilibrium that
is required - not a pressure reading. Any comments on the feasibility would
be gratefully received.
>
> It's good theoretically, except the air pressure needed to move an ASI
> needle is really minuscule - it will be about 25 times more sensitive
> than the gauge depicted in the Rotax service manual. You'd need a pair
> of really narrow-orificed restrictors - and exactly equal in size - to
> dampen wild needle waggle, and possibly putting too much lag in the
> system for a usable balancing instrument. From what I've seen inside
> several ASI's - long story short - repositioning the pointer and
> defeating them "Rube Goldberg" multiple spring tensioners (actually
> calibrators), it looks a bit of a challenge. But if indeed an "old
> ASI," let us know how it worked!
>
> Best,
> Fred F.
Many thanks for your advice Fred.
I had thought that damping might possibly be a problem.
I think I will experiment with a simple manometer. Having sufficient fluid
in the bottom of the 'U' will act as a damper.
Regards,
Roger.
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