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22FZB carb again

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22FZB carb again
Jack in the Box Offline
aka Alan Osborne
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Location: East Sussex
#1
06-10-2021, 10:18 AM
Most of the 22FZB's that I have seen have what appears to be a home made shield fitted near the slow running device as shown on the photo below.
Does anyone know what it is supposed to do please?
Thanks Alan


.jpg   InkedChummy carb_LI.jpg (Size: 965.55 KB / Downloads: 321)
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Mike Costigan Offline
former 'Grey Mag' editor
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Car type: 1938 Talbot Ten Airline
#2
06-10-2021, 10:24 AM
Not home-made, this was a standard feature; I'll leave others more technically minded to suggest its purpose!
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Parazine Offline
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Car type: 1927 Chummy, 1926 Top Hat 1938 Big Seven 1/2 a Trials Chummy
#3
06-10-2021, 10:42 AM
Stops large bits going in the auxiliary air intake - Nicholson refers to the slow running arrangement as an auxiliary carburettor, he probably near the truth.
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Mike Costigan Offline
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Car type: 1938 Talbot Ten Airline
#4
06-10-2021, 10:54 AM
But there's nothing to stop even larger bits going into the main air intake  Big Grin
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Parazine Offline
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#5
06-10-2021, 11:13 AM
True enough!
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Jack in the Box Offline
aka Alan Osborne
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Location: East Sussex
#6
06-10-2021, 11:42 AM
Thanks both for your replies.

We have 2 A7's fitted with this carb. One has a shield and the other doesn't and has not had in 8 years of ownership. Its idle speed has always been too high and I'm wondering if the open, threaded hole for attaching this shield may be the source of an air leak. I have now made a shield and fitted it. Weather has delayed road testing, but we'll give it a go today.

Alan
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David.H Offline
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#7
06-10-2021, 07:44 PM
I notice you have an extension on the "pin" ....I always found it a fiddle to lift it, so what a good idea...does the extra weight affect the needle valve?
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Dave Mann Offline
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#8
06-10-2021, 08:08 PM
Whilst I've seen those shields on 22FZ carburettors I've never seen them on 22FZB carburettors which don't have a mounting screw hole.    
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Hedd_Jones Offline
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Car type: '28 GE Cup. '28 AD Chummy '30 RL Saloon. '34 RP Saloon. Too Many toys!
#9
06-10-2021, 08:26 PM
is that an EGR valve Dave?
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Jack in the Box Offline
aka Alan Osborne
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#10
06-10-2021, 09:44 PM (This post was last modified: 06-10-2021, 09:48 PM by Jack in the Box.)
David,

This was the arrangement on our AD when we acquired it. It is certainly easier to fill the float chamber for cold starting than our Box, that does not have this feature.

There will be slightly higher mass as you say, so maybe the fuel level in the carb is slightly different too.

Alan
Dave,

Please accept my apologies if I have used the incorrect designation. The carb is bronze, so should I have called the thread “22 FZ again” ?

Do you know what the shield is for?

Cheers Alan
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