[ihc] RE: Circuitous idling

["Jim Grammer" <jgrammer@xxxxxxxxxx>]

>Date: Mon, 10 May 2004 10:17:27 -0700
>From: Joel M Brodsky <jmbrodsky@domain.elided>
>Subject: [ihc] Scott Machalk and his high rev

>There is an ongoing debate with the
>mechanics of/in history about whether or not these screws control fuel or
>air.  Everything I've read says that these are called Idle Air Bleed
>Adjustments, so why does the truck quit when you turn them in?

Depends on the carb design. In our Holleys of interest, the idle screw
meters the flow of fuel into the idle discharge passage(s) in most cases.
Examples are the 2300, 2210, 1904, 1910, and most of the 4xxx series 4bbl's
IIRC. A noteable exception is the 4160 circa '73, which meters air into an
idle emulsion setup. I have strong suspicions that this was emissions
related and intended to limit the idle mixture adjustment range.

Jim