Quote:


I'm not clear on where the needle and seat is on this carb.


Get yourself a copy of Mike Urich's little book on Holley 4150/60 carburetors, new or used. It's got good pictures and diagrams, and is pretty easy to read.

What you are seeing is the result of too high a fuel level in the secondary fuel bowl. The answer others have given a likely reason as to why it is overfilling. The book will help this all make sense.