I have a 350 sbc with a 274/286 duration cam and want to use the Q-jet I have on it. I've been told the idle characteristics (due to small idle circuit; lack of adequate vacuum at idle) won't be good. Anybody out there using a Q-jet on a 280-plus duration engine?  

i really don't see much of a problem..

i ran a 290 duration .575 lift cam in my 408 rat for a bunch of years... with a Qjet.. never had any problems...

there are several good carb gurus that do Q jets...

some people just don't understand how to properly tune a q jet.. so they tell you to not use them...