well I picked up a used HW off a 75 2.3L that had been a test engine at school. really crudy on the outside with old varnish but inside was spotless so I am gonna attempt to try it as is for now. so yesterday I got my cliffy adaptor and plan on bolting this all up tomorrow. I have linkage issues solved and will be running the water choke (does anyone know if a generic holley electric choke fits it?) I also have an aircleaner or two for it (a pinto air cleaner and a small 8" round aircleaner) as far as jetting should the stock 2.3L jets work out fine? I had another parts carb with the same jets but figured I could drill them out if needed. the only other question I had was that there was a vac line coming off th top of the carb right under the airclaner mount that feeds into a passageway in the carb itself. what is this for?