you need to do is remove the 'choke horn' housing away
from each side of the center boss and vent tubes by
cutting carefully with a hacksaw, and clean them up
with a file or die grinder.
the bowl vents
HOLLEYS: (some are integrally
cast or some have steel inserted tubes sticking
up between the venturi's at the front and the back
just inside the 5 1/8" neck diameter).
front Vent is OK if it is not over 1 3/4" high
as measured from the carb neck surface (where an air
cleaner would normally sit on) and the rear vent needs
to be kept no taller than around 1 1/4' When you cut
the vents make sure you angle the top about 45 degrees
with the tallest part of the angle toward the center
of the carb and the lowest part of the angle toward
Demons all you need to do is lower the rear vent about
you will need to remove the front and rear bowls and
put a rag in the top of the carbs to stop filings going
down into the air bleeds etc.
you are not confident to do this , any performance
carburetor or competent machine shop could do this
for you. It is a common and relatively small job.