CorvAircraft> alternative carbs

[Mark Langford]

Jim Wickert wrote:

>>Mark Langford is probly onr of the most experienced with the Dellorto and
the corvair for aircraft use.  He has comments in hiw web regarding his
findings with the weber.  I can tell you if was simple to setup and use Mark
would have used the weber but he elected after some work not to use it.  I
find the Dellorto and Weber type carb to be fickle when working at changing
altitudes.  <<

I'm not sure I've ever actually seen a Dellorto in person, but I do know my
way around Webers.  I didn't fly my Weber 40DCOE because I was going to
mount mine on top and couldn't figure out how to run carb heat to it without
a hideous cowling.  Aesthetics mean less to me now, and I think I could make
that work.  Altitude compensation is another matter, but there was some hope
that it work by  introducing an intake manifold leak that would allow
leaning at altitude.

Webers can be made to run very smoothly over a wide range of throttle
settings, and under radically different operating conditions, which is not
something the Ellison impresses me with.  Even sitting on the ground,
changing the throttle setting requires resetting the mixture, although maybe
I'm just more sensitive to that than most people because I have a mixture
gauge that tells me exactly where optimal air fuel ratio is.  My idea of
"rough" is subjective too, as I have the smoothest running engine that I've
ever flown behind.  And one could always argue that it's not set up
properly, but there's not much to set up on the thing, and even Ellison just
says "hmmmm" when I explain the lack of consistent air/fuel ratio throughout
the range.

I do know that at cruise if I go full throttle I'll have to fiddle around
with the mixture to keep it from running rough, and I don't think  a Weber
would require that kind of constant attention.  I haven't flown one, but
John Martindale has, and he'd be better prepared to answer those questions
than I would.  I do feel pretty certain that a Weber would provide a more
homogenous air/fuel charge to the six cylinders than the Ellison, despite my
convoluted intake system.  I've toyed with replacing the Ellison with the
Weber, and next time I'm in the mood to modifiy the cowling, I may do that
just to see how it does.  I think I already know the answer to that one
though.  It's not that the Ellison doesn't work OK, it just doesn't work
like I think any reasonably good carburetor should work.  But like I said,
I'm probably using an automotive yardstick, rather than the airplane
measure.  The Ellison does get the job done with zero maintenance problems
so far, so perhaps I shouldn't complain...

Mark Langford, Huntsville, Alabama
see KR2S project N56ML at http://home.hiwaay.net/~langford
email to N56ML "at" hiwaay.net
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