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Updraught Zenith carb setup questions
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Ittagub



Joined: 10 Nov 2016
Posts: 2

PostPosted: Thu Nov 10, 2016 11:35 am    Post subject: Updraught Zenith carb setup questions Reply with quote

Hello,

Currently I am trying to get an updraught zenith to work propperly.
About the carb.
It is an US bronze zenith reportetly from 1910. diameter at the butterfly 54 mm !!
It has a powervalve which is actuated through a mechanism at the butterfly axle. This mechanism can be adjusted.
Venturi 44 mm. There is also a smaller secondary venturi around the "double tubes"
At this moment suction jet 190, constant jet 170, power valve 90
I am familiar with the idea of this sort of carbs. It has a constant flow circuit and a "suction" flow circuit.
The power valve feeds into the constant flow circuit.
I have a lamba meter in the exhaust and am getting some idea whether I should use smaller or bigger jets.

My problem: air/fuel mix is going in all directions under accelerating and different speeds. Testing on the road is a bit difficult because I am living in a densely populated area.

Should the jets for the two circuits be of approximatly the same size? Or should they be of different size?
Any recommendations about the moment the power valve is opening in relation to the opening angle of the butterfly and jet size?



Hope for some advise

Thanks
Lex
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Penman



Joined: 23 Nov 2007
Posts: 4165
Location: Lancashire

PostPosted: Thu Nov 10, 2016 1:24 pm    Post subject: Reply with quote

Hi
Don't know if this will help or not, but starting on this page there is quite a lot of explanation about Zeniths.
http://old-carburetors.com/1927-Dykes/1927-Dykes-061.htm

The page advance is just above the image of the original page.
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Bristols should always come in pairs.

Any 2 from:-
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Ittagub



Joined: 10 Nov 2016
Posts: 2

PostPosted: Thu Nov 10, 2016 2:27 pm    Post subject: Reply with quote

Page seems not to be existant
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Penman



Joined: 23 Nov 2007
Posts: 4165
Location: Lancashire

PostPosted: Thu Nov 10, 2016 3:17 pm    Post subject: Reply with quote

Hi
Opens all right for me.
I've tried it on IE, Chrome and Firefox they all work
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Bristols should always come in pairs.

Any 2 from:-
Straight 6
V8 V10
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Rick
Site Admin


Joined: 27 Apr 2005
Posts: 21213
Location: North-west UK

PostPosted: Thu Nov 10, 2016 3:19 pm    Post subject: Reply with quote

Penman wrote:
Hi
Opens all right for me.
I've tried it on IE, Chrome and Firefox they all work


Opened for me ok too

RJ
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Rick (OCC Admin)
Various 1920s-1960s - Austin, Morris, Commer, Dodge etc.
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Peter_L



Joined: 10 Apr 2008
Posts: 2370
Location: New Brunswick. Canada.

PostPosted: Thu Nov 10, 2016 4:15 pm    Post subject: Reply with quote

Penman wrote:
Hi
Opens all right for me.
I've tried it on IE, Chrome and Firefox they all work


Me too MS Edge
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