Zenith 32 strange hole

[Alexis Collaud]

Hello,
I'm struggling with my Cyllinder #4 on my 1600S (616/12): when I remove the engine spark plug it doesn't have any effect when at idle. But when driving everything is Ok even if not perfect (the engine have recently fully overhauled)
Anyway, I have checked ths pistons, compression, did some air leakage tests ... it seems OK. Ignition is OK

I suspect the Zenith32 and I removed it (again) for a test and I've noticed a small hole, just below the venturi that looks "nice" but is not present on the other side.
This hole is connecting with the chamber behind

I join some pictures to make it clearer :

With a light behind to make it more visible

I don't have it on the other side:

Seen from the chamber behind

On the other side I have the two holes which for me are normal

Any idea ?
thank you

[Jacques Lefriant]

Hi
that area on the side is for a choke.
j

[Ron LaDow]

That is a drain hole for fuel which might get into an area used for 'enrichment' on starting; ignore it and thank the Z engineers.

[Alexis Collaud]

Thank tou !