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For some time the idle speed on the Ruby has been variable. I put it down to wear in the spindle but it now seems to have got much worse. I can set the speed and all is fine for a day or two, then it fails to idle, I increase it and find the next day it's over revving. I've marked the adjustment screw and it's not adjusting itself. I get the impression that when it idles slowly the mixture is richer.
The float chamber is clean, the valve is closing correctly and I have lapped the emulsion block and replaced the gasket. The flange gasket is also new.
Any ideas?
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Location: Essex
The mysterious hidden jet?
Joined: Aug 2017 Posts: 809 Threads: 72
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Ok thanks Nick, I've never investigated that, maybe I should.
Joined: Dec 2017 Posts: 1,132 Threads: 66
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Location: Nottinghamshire. Robin Hood County
Car type: Austin Ruby Mk1 1935
Peter be careful if removing this jet as it can be easily damaged. I cleaned mine without removal with a can of carburettor cleaner. For those unaware of the hidden jet it is on the underside of the carb behind a brass screw.
John Mason.
Would you believe it "Her who must be obeyed" refers to my Ruby as the toy.
Joined: Aug 2017 Posts: 809 Threads: 72
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Thank you both, that's a job for next week. I'd be surprised if the jet has ever been out before so I will try cleaning it in situ first.
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Great, thank you. A useful looking tool.
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Location: St Tudy North Cornwall
Have you checked the flatness of the carb flange? I recently found bowing on the carburettor flange was allowing an air leak between it and the manifold was enough to make idleadjustments impossible to set reliably. Lapping this flange flat again could well solve it.
Certainly worth investigating before you do anything more invasive on the carb itself. There's usually a simple solution to what appears to be a more complex problem!
Good luck Bob
