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SU carburettors

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Sydsmith
Posts: 696
Joined: Sun Feb 14, 2016 11:15 pm
Location: Aberystwyth Wales

SU carburettors

Post by Sydsmith » Wed Aug 01, 2018 8:19 pm

Recently there have been a couple of listings on fleabay of SU HV4 carburettors, in both cases pairs by different sellers.

In both cases they are described as down draft.

I have always thought of SU carburettors as side draft, am I wrong or are there two types of HV4, down and side draft?

Big Col
Posts: 316
Joined: Tue Feb 16, 2016 12:45 pm
Location: Leeds

Re: SU carburettors

Post by Big Col » Wed Aug 01, 2018 9:36 pm

Could it be that the impression of down draft is thought due to the inclined angle of the carburettors on the Daimler engine.
Colin,
I may be slow but I’m rough as well !

Stan Thomas
Posts: 466
Joined: Sat Feb 13, 2016 2:14 pm
Location: Penkridge. Staffs.

Re: SU carburettors

Post by Stan Thomas » Thu Aug 02, 2018 7:34 am

You are correct, they are side draught carbs.

Sydsmith
Posts: 696
Joined: Sun Feb 14, 2016 11:15 pm
Location: Aberystwyth Wales

Re: SU carburettors

Post by Sydsmith » Thu Aug 02, 2018 1:33 pm

Thanks both, thought I had missed something.

My 15 has had a Solex down draft fitted at some time which I have had trouble setting up. I have bought a replacement HV4 side draft which I have refurbished and was wondering before I fit it and tweak the controls if I had the right carb.

Hence the question. Syd

Bob Frisby
Posts: 23
Joined: Sun Feb 21, 2016 5:30 pm
Location: Boise, Idaho USA

Re: SU carburettors

Post by Bob Frisby » Sat Aug 04, 2018 9:28 pm

Gentlemen,

My understanding is that the "H" in our ordinary S.U. carb models (H2, HS4, etc.) stands for "horizontal", i.e. sidedraft.
Oddly, I have seen setups referred to as "semi-downdraft" where H-series carbs were used, tilted at a slight angle from horizontal!

I've heard of "vertical" or downdraft S.U.s, and thought they were designated "V". Possibly used in non-standard applications such as military vehicles. I don't know what to make of "HV" carbs. Hope someone follow up with more info, Id love to learn more.

Bob Frisby
Boise, Idaho USA
DB18 & DF302 Empresses

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Vortex O'Plinth
Posts: 739
Joined: Fri Feb 12, 2016 8:15 pm
Location: Gloucestershire

Re: SU carburettors

Post by Vortex O'Plinth » Sat Aug 04, 2018 10:19 pm

S.U. certainly produced downdraft as well as sidedraft carburettors......
17a861df4286b9f4-490ff986d54bc0b9DSC02737.JPG
In this case the piston return was with spring assistance only since gravity was not going to help.

This catalogue gives an idea of the wide range of S.U. carburettors produced.
Nick

Pas d'elle yeux Rhône que nous.

Sydsmith
Posts: 696
Joined: Sun Feb 14, 2016 11:15 pm
Location: Aberystwyth Wales

Re: SU carburettors

Post by Sydsmith » Sun Aug 05, 2018 6:06 pm

Nice picture "Mr O'Plinth" something I have never seen before, you learn something every day.

Bullens http://burlen.co.uk/?___store=default are of course the font of all knowledge on SU and many other Carbs, there is a load of interesting reading on their site, too much to report here, but a quick read did not show anything about H for Horizontal and V for vertical, certainly the HV4 I have is a side draft so perhaps that is a red herring? Nice try though.

When I was doing research for the right Carb for my 15, I did not find it easy to identify the correct item, but Dave Bennett (Capt Bobo) kindly chipped in and between us we sorted what appears to be the correct type, but we shall see when it is fitted.

Sadly HV4's were used on Bentley and Alvis cars in pairs and in singles on some 15's so they rarely come up in singles.

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