Float level Zenith updraught Carburettor

[john williams]

I remember an article in the "Grey Mag", a few years ago, written by someone from Holland, on how to measure the float level on the Zenith updraught carb'. I have searched all the Magazine Index, but can find no reference to this article. Anyone recall the article? I cannot get my float level correct by trial and error, and washers under the needle valve.

[AustinWood]

A7 Components stock the Zenith 22FZ handbook which very good.
The level can be measured in the tube in which the slow running jet fits.
I do this by removing the slow running jet tube and putting a length of clear tube down the hole.
The tube fills up to the fuel level.
Then close the top end of the tube with a finger and withdraw the tube.
Provided the tube is quite small bore it will keep the fuel in the tube and this shows the fuel level.
I have a tube with a washer pushed over it which is a tight fit and it is marked with the position the fuel should reach.
The tube is dropped in so that it sits on the washer and when it is withdrawn the amount that the level is out can be seen.
The level can then be adjusted by moving the collar on the needle valve as described in the handbook.
It's rather fiddly.

[Rick F]

A7 Components stock the Zenith 22FZ handbook which very good.
The level can be measured in the tube in which the slow running jet fits.
I do this by removing the slow running jet tube and putting a length of clear tube down the hole.
The tube fills up to the fuel level.
Then close the top end of the tube with a finger and withdraw the tube.
Provided the tube is quite small bore it will keep the fuel in the tube and this shows the fuel level.
I have a tube with a washer pushed over it which is a tight fit and it is marked with the position the fuel should reach.
The tube is dropped in so that it sits on the washer and when it is withdrawn the amount that the level is out can be seen.
The level can then be adjusted by moving the collar on the needle valve as described in the handbook.
It's rather fiddly.

All the above is why my chummy-engined special has run happily on a nice, simple 24T tractor carb for the past five years!

[john williams]

I remember an article in the "Grey Mag", a few years ago, written by someone from Holland, on how to measure the float level on the Zenith updraught carb'. I have searched all the Magazine Index, but can find no reference to this article. Anyone recall the article? I cannot get my float level correct by trial and error, and washers under the needle valve.

Thank you Jim, your answer matches what I remember from the "Grey Mag" article. However what I need to know is the hight of the level inside the indicating tube. Would it be possible for you to measure the indication mark on your device?
John

[AustinWood]

At the moment I can't put my hand on the Zenith manual. From memory the float level should be 1mm below the main jet.
My level measuring device is in my Austin in the garage on the other side of the town. I am over there regularly and shall retrieve it later.

[Ian Williams]

I agree that sounds like the correct level, but to clarify you need to remove the main jet, replace the screw in plug and the fuel should sit 1mm below the top of the tube the main jet fits into. You can of course measure all this with a vernier and make up at measuring tube as Jim describes which is far easier than setting up a remote tank on the bench and viewing the main jet down through the choke tube.

[john williams]

I agree that sounds like the correct level, but to clarify you need to remove the main jet, replace the screw in plug and the fuel should sit 1mm below the top of the tube the main jet fits into. You can of course measure all this with a vernier and make up at measuring tube as Jim describes which is far easier than setting up a remote tank on the bench and viewing the main jet down through the choke tube.

Thank you again Jim, and Ian. I now have the spec's I need to check the level accurately. John