Vintage carb fuel level

[k. rogers]

Can anyone tell me the correct level of fuel in the vintage zenith carburettor please? The zenith literature tells you that it needs to be 3mm below the top of the main jet cover but this is impossible to ascertain with the carb in situ, however, this will correspond with the level in the float chamber!

[k. rogers]

Well, I've done a very careful measure taking a level line from 3mm below the top of the main jet cover and reckon half inch below the top of the fuel chamber is about right! Does anyone agree?!!

[Forumadmin]

Does the diagram of the carb not show the fuel level?
Prewar tech notes say this.

Popping back in the silencer down hills means weak mixture - clean slow running jet first.

This may be caused by E10 petrol!

[k. rogers]

Unfortunately, there is no diagram showing the fuel level, the only specification I can find is the 3mm below the top of the main jet cover, so that is what I've tried to project onto the float chamber. I will check the slow running jet again, just in case something has found its way in there. I've never put E10 in the vintage, so it can't be that. Thanks for your input, Keith.

[Keith Clements]

zenithd.jpg

Does this help?

[k. rogers]

Yes and although it shows a vertical choke carb, the principal is the same. I would say the level shown is the 3mm below the main jet cover which I have achieved with mine. So I'm satisfied that my fuel level is not to blame!

[Keith Clements]

I did a search using the Archive Search facility and found this useful document.viewtopic.php?p=45160
The search found 266 documents with Zenith in them so there may be other useful references.
See also the pre-war library. viewforum.php?f=95

[k. rogers]

So, guess what? After checking every conceivable item on the ignition system to rule out anything that might cause my misfire, the last thing was the slow running jet which was last checked when I did all the work on the carb. Held it up to the light and could see the orifice was not completely circular! So I soaked the jet in strong detergent for an hour then rinsed it and blew it through with compressed air. Gave it a short run and there was no backfire! So now I can play around with the smaller main jet and choke tube until it's spot on. Thanks Keith for that prompt, sometimes it is the simplest of things!