[TR] zenith or su's ?

Wayne Lee wayne at motorcarriage.com
Tue Dec 1 07:46:18 MST 2009


Hi Jim,
   Yes, You have to consider the Springs as they enter into it just like the 
Viscosity of your oil in the Dash Pots.
But, Actually it's the other way around the softer Springs will let the 
Pistons rise too soon as You say, but this
makes the mixture too lean. It's when the Springs are too stiff or stiff 
enough as needed, that it will keep the Piston
down and draw more Fuel through your Jet relative to the volume of Air 
through the variable choke effect or Venturi.
  The same applies, but only momentarily when too thick of a viscosity Oil 
is used in the Dashpots. The thick oil restricts
the rising rate of the piston which then acts as the accelerator pump would 
on non CV Type Carbs.
  I run the middle strength spring, I think green color coded on mine.
Wayne Lee
wayne at sportsracer.com
wayne at sucarb.com

--------------------------------------------------
From: "Jim Muller" <jimmuller at rcn.com>
Sent: Monday, November 30, 2009 9:40 PM
To: "Triumph List" <Triumphs at autox.team.net>
Subject: Re: [TR] zenith or su's ?

> On 30 Dec 2009 at 17:23, Wayne Lee wrote:
>
>> Yes, the Spitfire Float Bowls are essential in getting it right.
>
> Also consider the springs.  They must match the expected airflow.  If
> they were from a smaller engine, they will be too soft and the
> pistons will top out too soon.  This will make the mixture too rich
> at higher flow rates.  If they were from a larger engine they will be
> too stiff and the pistons won't open up enough.
>
> -- 
> Jim Muller
> jimmuller at rcn.com
> '80 Spitfire, '70 GT6+


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