Interesting problem that I have encountered before. The Strombergs have a
diaphrame so the piston is ruled by an accurate depression while the S.U.'s
have a static clearance that can vary. Its not likly BUT the clearance may
be too large on the SU's between piston and dashpot. More than likly though
the needle and seat are too small for the flow demand. I have almost always
needed to increase the flow of the needle and seat by drilling out slightly
(sorry don't remember those numbers). I also drilled the main jets as you
have suggested. I have used a #38 drill .101", and a #37 drill which is
.104". The #37 more than does the job so I would use the#38 first and see
if there is any improvment. Do check the float levels though as this puppy
just might be not be able to flow the dmeand of the engine.
----- Original Message -----
From: Jack W Drews <vinttr4@geneseo.net>
To: <fot@autox.team.net>
Sent: Friday, January 21, 2000 7:07 AM
Subject: SU carb fuel flow
> I'm interested in some input from the real experts -- Kas, Hardy, Jack,
> etc --
>
> Last year I switched from Strombergs, which wouldn't corner but which
> made me run like stink down the front straights, to SU's, which
> performed properly in corners but lost me several hundred rpm's down the
> straights. My exhaust gas temps indicated that the car was running
> leaner even though I was running very very skinny needles.
>
> Some measurements I've made using a fuel flow measurement device
> indicates that I can make the SU's flow the same amount of fuel as the
> Storm's by enlarging the main jet tubes by a few thousandths.
>
> I'm interested in your comments on this modification.
>
> --
>
> TR6 -- 29 years old
> TR4 -- 39 years old
> uncle jack -- 49 and holding
>
>
>
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