What is that?!

[808-dartGT]

I just pulled 1920 carb of my 1964 dart 225, looks like hole was plugged up with epoxy blob, what does it do? Hole looks like original

 

[AJ/FormS]

IDK; wait until you get inside; maybe it will be obvious.

 

[808-dartGT]

I figured out, it’s like a breathing opening behind accelerator pump, I guess to detect early leak if diaphragm is failing? I can’t think of any other purpose.. so previous owners long time ago decided to fix it that way, I put it back together and cleaned it up of course with some fresh diaphragms, it’s running ok, gotta tune later.

 

[67Dart273]

I doubt it's for the accel pump I'd try and trace it out again. It was considered necessary when the carb was designed..........................

 

[pishta]

I think the OP is right, its a accelerator pump breather/weep hole. I had one on a 1920 that actually spewed fuel out when the pump seal went bad. It was unreal, a jet of fuel just streaming onto the intake/exhust manifold. I put a pic of it somewhere on this site 5-6 (8!) years ago. IIRC, mine was behind the bowl casting too. Found a great post with a pic and explanation of its purpose.
Holley 1920 carburetor is leaking gas on my 72 /6 duster - Slant Six Forum

 

[pishta]

Holy necro-post 808-Man, that link is a link that I posted too back in 2011! And its my pic too....

1920 has a leak in another place

 

[808-dartGT]

Holy necro-post 808-Man, that link is a link that I posted too back in 2011! And its my pic too....

1920 has a leak in another place

I read both posts, and that confirms it