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Re: carb conversions

To: spitfires@autox.team.net
Subject: Re: carb conversions
From: Dan Buettner <danb@thelittlemacshop.com>
Date: Sat, 1 Sep 2001 20:05:37 -0500
>But the 2 1.25" SU's with their combined 2.12" area is still better 
>than the single 1.5 ZS with 1.766", right?
>
>Joe


Yes - and no.  Depends on the size of the engine, among other things. 
Carbs have to be sized appropriately to the motor.

If one were to put a pair of really stinkin' big SUs on a Spitfire 
motor, I would imagine that it wouldn't run well at all.  The air 
velocity going through the carb body might not be sufficient to draw 
enough fuel up out of the jet, and atomization might suffer as well.

On the other hand, carbs that are too small will effectively cut the 
engine's breathing ability, as air simply can't travel into the 
cylinders fast enough.

All that being said - yes, I would venture to say that two 1-1/4" SUs 
are better for a 1500 than a single 1-1/2" Stromberg.  From 
everything I've heard, two 1-1/2" SUs are even better for the 1500s 
... the same might not be true for the 1147cc and 1296cc motors, 
though!

Dan
-- 
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Dan Buettner  -  Des Moines, Iowa  -  mailto:danb@thelittlemacshop.com

1957 TR3, TS15098L 'O' - in re-assembly stage.

1977 Spitfire, FM64159U 'O' - in storage.

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