Carb draining?

When I was in auto shop in the early 70s I remember a problem with leaking on the Quadrajets. IIRC, if you remove the throttle body there is a plug in in a cavity under the bottom of the float bowl. Don't remember if it screwed in or was pressed in, but they tended to leak. Some of the rebuild kits had a foam pice that was supposed to be put into the cavity over the plug & then was held in place when the throttle body was put back on. It was supposed to seal up the leak. Our shop teachers usually told us to leave out the foam piece & instead we covered the existing plug with epoxy. Don't know if this is your problem but might be worth checking out.