Larger venturi for 2.2L Zenith carbs?

[SoCal_Lynch]

I apologies if this has been covered and I didn't find it, I did try searching. I have a 2.4L running the earlier engine Zeniths and want to swap in a slightly larger venturi size but am having trouble finding where to source those.

Can anyone suggest a source/approach?

Thanks in advance.

[john walker's workshop]

Webers actually fit the bore but are a bit shorter in height.

[SoCal_Lynch]

Thanks for the fast response. Do they function the same despite the height difference?

[Hi_Fi_Guy]

Many Solex and Zenith parts are interchangeable. This seller will have everything you need/want.
https://www.ebay.com/str/alfa1750scarburetorspartsstore

[SoCal_Lynch]

Thank you for the link/source.

So if the zenith carbs are fine, except for the Venturi, not allowing him to flow adequately, it would seem like using a slightly larger interchangeable Weber venture would be a very cost-effective way to address this challenge.

Curious why this isn’t a more commonly done thing if that’s actually how it works out?

[Hi_Fi_Guy]

I’ve gone full rebuild with larger Venturi and rejetting. A noticeable improvement but if you’ve ever driven a car with Webber carburetors I doubt you will be satisfied. Wile there is nothing wrong with Zeniths, they were designed to meet smog regulations, not for performance. They don’t offer the immediate throttle response you would get from a pair of Webbers. The Zeniths are more progressive but less performance oriented. In the end I went with PMO carbs and couldn’t be happier.

[SoCal_Lynch]

Thanks Brian, appreciate the follow-up.

[Bobboloo]

Another alternative is you could have the venturis bored to the larger size.

[targa72e]

As others have mentioned, Alfa 1750 has all the parts you need.
One of the limitations with Zeniths is if you get too far away from stock configurations the emulsion tube design and lack of different emulsion tubes make it difficult to get high RPM mixture correct.
I have a modified set of Zeniths on a 2.5 with Mod S cams. I had to play around quite a bit with the main air jet as I was lean above 5500RPM. Eventually you reach a point of diminishing return where larger jet doesn't improve upper RPM mixture.
I consider a wide band O2 set up as mandatory for getting things dialed. Low and mid range tunning was pretty easy and straight forward but getting the upper end correct was more challenging.


john