dave,thanks for your reply,adjusting idle screws make slight differences,but i had to open the second [rear] chokes to allow the front blades to operate within the limits of the progression holes/slots in the carb,otherwise it floods big time! does the second chokes have progression slots as they seem to be there in the carb veturis?[no power valve fitted to rear metering block].is the holley 800 too big! as i was told it should have a 850???????