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"I think there is a bit of confusion here.
There never was an HS1 SU - The HS range started at 1 1/4" HS2, as used on Minis, Minors 1100's etc."
That will have been me getting muddled.
Jamie.
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I know it is off the subject but I am using a D2 SU on my Ulster replica. It is a 1 1/8 inch down draft originally fitted to a wolseley 8 and works well on my engine..
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Location: Rokeby, Victoria, Australia
Car type: '27 Chummy, '34 Special, '50 Traction Avant
I use a H1 1 1/8",I think from a Mk1 Sprite they look more "vintage" than the later types and are still available but maybe not for 5 quid.
Cheers
Mark
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Location: Malvern, Victoria, Australia
18-04-2019, 04:22 AM
(This post was last modified: 18-04-2019, 05:50 AM by Tony Press.)
From the book 'Skinners Union History' by Mike Harvey published by The SU Carburetter Co.-
1925 2M vertical dashpot carburetter in the 'moderm' style introduced with bronze body superseding the Sloper type.
1928 HV new series similar to the 2M but cast in Mazak with a bottom feed float chamber, in a range of sizes.
1930 The top feed float chamber is added.
1930 The OM Carburettor is introduced- a new 1" used in twin and triple installations on sportscars.
1931 The D series of downdraft introduced with a piston spring for the first time.
1937 The H series of carburettors introduced in a range of sizes.
1938 Hydraulic piston damper introduced (not fitted to the T type MG until 1947)
1939 Brass or weighted aluminium piston introduced to replace Mazak (still no spring).
1948 Aluminium suction pistons and piston springs introduced, weighted pistons phased out. Springs have a reduced diameter lower end until 1955. The hydraulic damper rod is increased in wire gauge with two lengths.
1950 Carburetter is given an air breather hole for the dashpot in the front air filter flange and in some the air hole is deleted from damper cap with a vent passage in an angled web on the dashpot. The still brass cap has a knurled edge up to 1955 and if unvented is fitted with a fibre washer.
1954 HD series introduced with diaphragm jet assembly.
1958 HS series introduced (H series phased out in 1960)
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
Thanks Tony, but because of the sparse markings and interchange of parts the full picture is still vague. I suspect carbs without springs contd after 1948 and carbs without the diagonal rib after 1950. Unless have side by side or otherwise familiar with all, it is difficult to know which piston assembly have. Prior 1937 was there no flange for air cleaner?. And were mount holes horizontal until 1937? Was 1 1/8 available prior 1937?
The 1 1/8 1938-1950s with dashpot and ex Series E and Morris Minor is/was common and seems to suit Sevens well.
Joined: Aug 2017 Posts: 1,746 Threads: 42
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Location: Malvern, Victoria, Australia
19-04-2019, 12:56 AM
(This post was last modified: 19-04-2019, 01:26 AM by Tony Press.)
The book notes that various car manufacturers requested different changes to their SU's and I suspect there is no complete listing of all the variations.
I assume that if the manufacturer wanted an Air Cleaner then a front flange could be fitted to the earlier carburettors.
As far as I know the 1" OM carburettors had no front flange.
Not that an Austin 7 would usually be fitted with one but if the damper cap has no vent hole it should have a sealing washer and angled web with a drilled hole (not all with the angled web had the hole apparently - again all to the request of the customer).
