off list carb question

[Bruce Plecan]

I used to do alot of work with Webers, but don't recall seeing any CFM
related numbers for them.   They had been used on so may cars, that the
applications, had the chokes pretty well sorted out or picking a similair
engine to what you were working on would get you close to start with.   I've
seen 45s used with just a single tube intake, with the other side blocked
off.
   Now being EFI specific,  it seems to be *common* knowledge a GM dual 2"
TBI is 670 CFM, the 1.8" butterflies about 450.   Needless to say the type
of manifolding makes a huge difference for butterfly sizing, ie Independent
Runners allow for very large butterflies, and that is why the 45s seem to
always use such large chokes in em.
   I've used a reworked 45 in place of a Holley 600 CFM carb, with pretty
good results.
HTH
Bruce




> any one know how to work out CFM for a weber, eg 45mmDCOE?
> just would like to know how to work it out

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