[cpnbnanamn]

So.. My truck's carb was starting hard and not running like it should.. And looking at the carb, it looked gummed up, so I decided to rebuild it. I tore it down, and dunked it in a carb cleaner, and am in the midst of rebuilding it, when I discover this... Hole. It's apparent SOMETHING was in there.. but I know for CERTAIN, I DIDN'T take anything out of it.. According to the exploded diagram I got with my carb kit, it's for the 'valve-idle vent (BV)' Yeah. I'm confused. I thought I had a 'B' carb?? Now, I'm not 100% sure WHICH carb I have!! The numbers that I found on the inside of the top-half of the carb are 7025523.. And I'm not sure if that matches to anything relevant!! (Edit: From what I'm reading, that's a casting number, and not relevant.)
HELP!!


1967 Chev C10 SWB Stepside with a L-6 250 CID engine, manual trans, manual choke.