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+--- Thread: Preferred SU ? (/showthread.php?tid=3774)
Preferred SU ? - stevenm - 16-01-2020
I’m working with a 22fz updraft with little success.
I read the SU side draft is the better performing but is there a preferred SU ? Can I put on an HS4 or any carb and needle or according?
Any thoughts appreciated.
RE: Preferred SU ? - leaf200 - 16-01-2020
The SU OM card fits on a ruby manifold they are used on Morris minors and MGs
RE: Preferred SU ? - Terry McGrath - 16-01-2020
I use a one inch side-draught pre-war SU bolted, with thin adapter, onto a ruby manifold with the restricting venturi orifice ground out.
This is on my RF saloon in place of the updraught Zenith. All-round improvement; simplicity, adjustability, starting and performance.
My theory is that Sir Herbert would have used S.U.s if they had not been owned by his arch rival.
RE: Preferred SU ? - bob46320 - 16-01-2020
I think you would be looking for an 1" / 1 1/8" SU carb. You would need the Ruby style manifold and you will need a block to change the mounting holes from vertical to horizontal. If you have the pre Ruby (Alloy up draught ) manifold, then you will need something a bit special making in the way of inlet manifold.
Also if you have a front tank, you will need a fuel pump or ensure the carb bowl is low enough for fuel to flow from tank to bowl.
See SU on this forum.
RE: Preferred SU ? - Alan - 16-01-2020
I use that set up on my Chummy, too. Only downside is as far as VSCC are concerned you are no longer “standard”. It works ok without a fuel pump as well.
RE: Preferred SU ? - Chris KC - 16-01-2020
Later 1 1/4" SU's also work fine and are easily picked up at jumbles.
RE: Preferred SU ? - Belinni - 16-01-2020
Later 1-1/4" SU with blue spring and no.6 needle works well
RE: Preferred SU ? - stevenm - 16-01-2020
(16-01-2020, 02:57 PM)Belinni Wrote: Later 1-1/4" SU with blue spring and no.6 needle works well
great tip !
thank you for the detail.
RE: Preferred SU ? - Douglas Alderson - 16-01-2020
Steve I belive if you change the manifold to the later type you will also need to adjust the exhaust pipe as the outlet is further over. As other have said they do work happily with out a pump and if you can find the right one you don’t need an adapter.
RE: Preferred SU ? - Tony Press - 16-01-2020
.
If using an early block remove the nice knurled nuts and replace with standard nuts before fitting the 'Ruby' manifold.