[ROVERNET - UK] Thanks for the help: SU carbs, stuck clutch.

Slatskars slatskars at comcast.net
Mon Jul 5 04:21:30 BST 2004

No, there is quite a difference between an HS8 and an HS6. The number refers
to the size of the diameter on the manifold end of the carb body. The number
is the number of 1/8 inches over 1 inch. A 6 is 6/8 or !-3/4 inch, an 8 is
8/8 or 2 inches in diameter, etc. Jet and needle size would be governed by
the particular engine specifications. Thus you could have an HS6 in several
different vehicles with different jets and/or needles. The needles and jets
can be changed but the bore size of the body is fixed. Normally the larger
the engine in CC's the larger the bore. For example a MG midget 1275 uses
HS2, and an MGB 1800 uses HS4, Rover 2000 would use HS6. The Rover 3ltr
(3000) uses one HD8 in standard configuration. In order to increase the size
of carburetor, you must also change the intake manifold to match. There are
four different types of SU carbs. The early H type for Horizontal, the HS
which is very similar but uses a different type of float and jet
arrangement, the HD which uses a Diaphragm, and the HIF which uses an
Internal Float. You can for example interchange between a HS4 and an HIF4
for a MGB if the linkage will work and the needles and jets are properly
sized. Hope this helps. This is not rocket science by any means.

I have been working on an interesting project for a friend who has a late
1500 CC MG Midget. We managed to obtain UK spec. SU's for this engine to
replace the single Zenith/Stromberg. They came complete with the manifolds,
but the jet assembly is entirely different than any US spec car. It would
however be a simple matter to change it over to a US spec HS jet assembly.
The dome and piston are also different, but could be changed over easily.
The body is the same, which makes for some interchangeability. As in why
reinvent the wheel?

SU carbs are quite basic units and pretty good trouble free devices once set
up properly. Needles are available to give leaner or richer parameters for
different applications such as high altitude or racing. They are very
interesting and flexible. Very little to wear except the throttle shaft and
their bushings.

Vancouver, WA, USA
----- Original Message ----- 
From: "T. Clemen" <tclemen at msn.com>
To: <rovernet at lyris.ccdata.com>
Sent: Sunday, July 04, 2004 5:04 PM
Subject: [ROVERNET - UK] Thanks for the help: SU carbs, stuck clutch.

> Thanks all, I will keep you posted on what works and how everything turns
> out.
> As far as the carbs go; is the only difference between a HS8 and a HS6 the
> needling and or jet size?  I would like to know if the front float chamber
> lid is interchangable with another BL auto or if I am stuck repairing the
> one I have.
> Thanks again for all the help!
> Tom C.
> PS for anyone wondering the Burlen site is "www.burlen.co.uk"
> this was a great site and very helpful.  Thanks Roar.
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