aussiesteve

Just set up a fresh 408,, with vortec heads edelbrock rpm and an isky 280 mega cam,, 1 3/4 headers,, msd pro billet etc,,

car ran ok at idle with a smaller cam and a 750 vacuume,
the new engine builder has upped the cam and i fitted a street HP 750 Double pumper,, all brand new!,,,,,carb wont idle under 1400rpm and is fluctuating 1350,1450rpm,,,,,,,,i pulled the PCV hose off the front of the carb while at idle and the rpms picked up!!!!,,i have seen most cars stall or stop running if there is a vacuume leak,,,the engine ran beautifull and wasn,t hessitating,,i put the hose back on at idle and the engine breathes like a 75 year old man with a smoking issue again idles at 1350 to 1450 rpm like S##T.,,,
whats going on,,,

car revs free and open throttle is as expected when revved at idle,,,,the thing just wont get down to normal idle 1000,, 1100,,like im used to,,,
cant wait to drive this thing,,
the cost of fuel will kill me

JaBoT

What is your timing at idle?

pancherj

You pulled the PCV which added air volume to the carb and the idle picked up...sounds like it is running too rich at idle and the extra air helped lean it out. Where are the throttle blades set at? The transition slots may be over exposed.