Joined: Jun 2018 Posts: 518 Threads: 90
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21-05-2022, 02:07 PM
(This post was last modified: 21-05-2022, 02:07 PM by Jamie.)
I wish to fit a 1 1/4" SU to my Ruby and am looking for a suitable inlet manifold. I am looking for a separate manifold as I wish to fit a bunch of bananas exhaust manifold as well.
If anyone has one they would be interested in selling, please let me know.
Thank you.
Jamie.
Joined: Aug 2017 Posts: 919 Threads: 18
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Location: North Yorkshire
If your SU is from a Morris Minor I think you will find that it has an AN needle. This was the standard needle and is a good choice for the Austin 7 engine.
Joined: Jun 2018 Posts: 518 Threads: 90
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It may be an AN needle: I cannot remember. I refurbished the device, fitting a new jet, spring, needle and butterfly spindle following suggestions from someone who has tested various combinations on a dynometer.
The plan is to fine tune the engine on the Dyno once I have sorted out the manifolds. I have made a number of modifications to the engine and I am curious about the final power output.
Jamie.
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Location: North Yorkshire
22-05-2022, 02:19 PM
(This post was last modified: 22-05-2022, 02:25 PM by Steve Jones.)
Has Tony Betts got no stock? That's where mine have come from and all the various options are in his list including the 30 degree.
Steve
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Good point. Monday phone call coming...
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Location: Auckland NZ
Car type: 36 Nippy, 31 RM, 38 Special, 24 Works Rep
I would advise against using a 1 1/4" Su, unless you have a reasonably well tuned engine it will be too big so metering will be even more of a compromise. You would be far better off with a 1" or 1 1/8" instrument. To clarify the reasons; for an SU to work manifold depression causes the piston to rise and fall depending upon throttle opening and engine speed. If you use an oversize Carburettor the piston will only move a small distance rather than fully open when required, therefore you are trying to meter the fuel on a very narrow band of the needle. The consequence of this is lower performance than optimum in which case you may do better with a refurbished Zenith, they work well in good condition. Although most that have been through my hands need new throttle spindles at the very least.
Black Art Enthusiast