After reading a very good internet article (link was provided on this
email list a few weeks ago), I think I would like to switch over to SUs
in the near future, because of the huge selection of needle profiles
available.
A few questions: HS6s are 1.75" and HS8s are 2", correct? Do HS8s
(assuming they are 2") fit the TR6 intake manifold? I assume that some
modification would be necessary. Is there a huge selection of needles
for HS6s? Can you use stock TR6 throttle linkage when using SUs, or is
there some modification necessary? Has anyone tried triple 1.75" SUs
on the Goodparts triple Stromberg manifold? Throttle linkage issues
with this setup?
I have a modified engine (ported/polished head, 9.5 compression, 1.65
roller rockers, GP3 cam, headers), and can't seem to get performance
right with the Strombergs. I am convinced that I could do a lot better
by playing with SU needles and the O2 sensor/mixture gauge that I have
in the car.
If anyone knows of internet links or good books on the subject of SUs
and performance, please let me know. Thanks!
Tim Holbrook
1971 TR6
--- Sally or Dick Taylor <tr6taylor@webtv.net> wrote:
> From: tr6taylor@webtv.net (Sally or Dick Taylor)
> Date: Wed, 14 Nov 2001 11:25:25 -0800 (PST)
> To: afterburn27@yahoo.com (Matt M.)
> CC: 6pack@autox.team.net
> Subject: Re: engine rebuild
> Reply-to: tr6taylor@webtv.net (Sally or Dick Taylor)
>
> Matt---One of the questions you asked was regarding the 2" SU carbs
> as
> worthy replacements for what you now have. The HD8 is a fine carb,
> and
> is on the Mark III Healey, as you know. The biggest advantage is the
> wide selection of needles for this unit, all being available from
> Burlen
> Fuel Systems, in England. You will want the Haynes Workshop Manual
> for
> the SU Carburetor, for guidance here.
>
> Proper selection of the needles is most important when building an
> engine. I will say again that it is a crap shoot, unless one has an
> air/fuel monitor, fed info from an 02 sensor in the exhaust. (Too
> much
> fuel can be as bad as too little when it comes to making power) An
> A/F
> monitor will give you a read-out along the rpm band under all
> conditions. While it is entertaining to experiment with different
> carburetors and their settings, it is rare that you will stumble on
> the
> right profile without the benefit of this most useful device. A dyno
> will report the power output, it won't necessarily tell you if you're
> lean or rich along the way.
>
> As mentioned by another enthusiast, the ZS carbs are also capable of
> flowing a lot of air. Needle selection here is somewhat limited,
> unless
> you are equipped to do a little conversion to make them capable in
> accepting the SU needles.
>
> I am envious of this great time in your life. I wish I could go back
> oh
> so many years and repeat them!
>
> Dick Taylor
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