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Re: Carburetion.

To: "Marcus A. Pryor" <banshee16@starband.net>,
Subject: Re: Carburetion.
From: "Stephen Wan" <Steve@olsonarchitect.com>
Date: Tue, 6 Jun 2006 14:11:45 -0700
Correct me if I'm wrong, but webers or mikunis use fixed ventury sizes whereas
the SU needle changes profile depending on amount of vacuum and air velocity.
How do they differ in maintaining correct air-fuel ratio when the fixed
venturi has one variable(air velocity) and the SU's have 2 (velocity and
needle profile)?

Steve
70' 1600
  ----- Original Message -----
  From: Marcus A. Pryor
  To: datsun-roadsters@autox.team.net
  Sent: Tuesday, June 06, 2006 12:59 PM
  Subject: Carburetion.


  The first thing lost is velocity of the air stack. This brings in the
  equation Bernouli's principle; that is, air pressure is inverse to speed.
  Since a carburetor requires a venturi in order to create a vacuum and pull
  fuel in, this creates a natural block to the air column. If that venturi
  is too big, the engine will be severly hampered, resulting in erratic fuel
  ratios.

  Ideally, the CFM of a carburetor should take into account the uses of the
  engine and rpm range. There are numerous methods used for this
  calculation, and a simple Google search will find various formulas for
  this calculation.

  Marcus A. Pryor
  For a new age of reason




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