72 Midget: SU Carb vents ?

[Chuck_Ciaffone_at_WG-RAL@smtp.wg.com]

     Big-time Top-down weather here in NC!
     
     While trying to "clean up" the engine compartment in my 72 
     Midget, I came across what looks to be just a fuel-bowl venting 
     system.  From the top of each SU fuel bowl, next to the fuel 
     inlet line, is a short hose that leads to a 1/4" pipe.  The 
     pipe then goes to the evap cannister.  
     
     When I removed the pipe and plugges the 2 hoses, the engine ran 
     badly.  No fuel getting into the bowl?
     
     When I unplugged the hoses, but left off the pipe, all ran 
     well.  As nothing appears to leak out of these hoses, is there 
     a compelling reason to replace them?
     
     chuck