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Bill,
On researching the Weber carb it seems it was originally developed to provide different chokes, one for low rpm and one for high rpm.
That would be good if we had siamesed PP with different sized runners - sounds complicated.
George ( down under)
George,
You are correct but remember the manifold efficiency is based on having the correct size runners to begin with. The venturi is needed to improve vacuum to draw fuel. The Weber has a secondary venturi as well, the little bullseye one in the middle. So things are complicated in any case. A well tuned FI is almost always better.
Bill Jepson
------Original Message------
From: George Lendich
Sender: Rotary motors in aircraft
To: Rotary motors in aircraft
ReplyTo: Rotary motors in aircraft
Subject: [FlyRotary] Re: Weber chokes
Sent: Apr 3, 2010 2:31 PM
Lynn or Bill,
Having a quick look at the web sites, I see the choke does restrict flow and
increase venturi effect, which is good for sucking up fuel from the float
bowl. However without maintaining that restricted size, through to the
combustion chamber, the flow returns to a slower flow. So I don't see a
benefit for increased VE without the smaller sized manifold inlet tube (
matching the choke size) OR a reducing diameter manifold inlet tube (a style
Lynn mentioned in an earlier post).
Or am I wrong?
George ( down under)
Lynn,
It is worth mention that on many Webers the "choke" is changeable on size.
Also many people don't understand thar choke means primary venturi, not a
starting restriction used on many big 4 barrel. carbs. I know this is
second nature to us, we grew up on this stuff. Many of our younger
contributors have never even worked on a carburetor. I used two 42 dcoe
Webers on motorcycle engines used om sports racers. We ran 38-42mm
venturis.
Bill Jepson
Sent from my Verizon Wireless BlackBerry
-----Original Message-----
From: Lynn Hanover <lehanover@gmail.com>
Date: Sat, 3 Apr 2010 08:59:29
To: Rotary motors in aircraft<flyrotary@lancaironline.net>
Subject: [FlyRotary] Weber chokes
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