Can you identify this bowl vent?

[leeklm]

Hello,

Am new to rebuilding quads, and finding Cliffs book to be a big help!  However, I am not sure about the vent slot on the rear outside of bowl.  This carb did not have a cover over the hole like others I have seen.  Do i need to find a cover from a donor carb, or can I just fabricate something?  What is the purpose of this slot/vent?

Ok, my pic was too large... But the vent hole is about 1" high and close to a 1/2" wide, it has two threaded holes for screws.

Thanks!!

[Ethan1]

 Can't see the pic.

[leeklm]

Here we go... had to reduce the file size.

[Ethan1]

 I believe that can be left open. I don't think there was anything covering it. Probably some sort of vent? Let see what Cliff says. Probably should be left open?

[Cliff Ruggles]

HIC, Hot Idle Compensator.  If used, the hole will be drilled thru and down to provide manifold vacuum.  A bi-metalic spring/valve sits over the hole, and opens up if underhood temperatures get hot enough and adds some idle air to the engine.

If the lower hole isn't drilled thru, the carb doesn't use HIC.  If it's drilled thru and left open, HUGE vacuum leak.....Cliff