If you are using carburetors with
a choke horns in-line or sideways you will need to
remove the choke horns. Many performance Holley's,
Demons and QFT's come with no choke horn direct from
don't remove the center threaded boss in the center
of the four barrels, the adapters are
designed to accommodate these or the thread boss
can be lower in the case of carbs that come with
no choke horn from the factory, leave them as they
are so you don't need to drill deeper
All 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.
Sideways Mount Setups will fit with no vent modification
the bowl vents (some are integrally cast or
some have steel inserted tubes sticking
the venturi's at the front and the back of
each carb just inside the 5 1/8" neck diameter).
Cut them to an overall height of 7/8" and
angle the top about 45 degrees with the tallest
toward the center of the carb and the lowest
part of the angle toward the bowls.
You will need to remove the front and rear bowls
and put rag in the top of the carbs to stop filings
going down into the air bleeds etc.
CHOKE HORN REMOVAL BY A CARBURETOR SHOP
If 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, but if you do have a carb shop do this ask
them to mill the center divider section of the
choke horn (between the front and rear barrels)
right down to the top of the venturi's, this would
certainly help air flow.
The SC520Streetcatcher will fit Mighty and Race
Demons which come with no choke horn from
and could be fitted to Street Demons with the
choke horn removed (re Holley Info above).
The only other
modification is that the Demons use a 5/16" diameter
center stud, which would require simply drilling
out the adapter center hole to 5/16": clearance
and changing the allthread studs from 1/4" to
5/16". Also on the Street Demons there
may have to be slight modifications to the
for bowl vent clearance.
FUEL TECHNOLOGY (QFT) CARBURETORSThe Quick Fuel
Technology Carburetors are the same
other than they have a 5/16" center stud
as does a Demon.
The SC520Streetcatcher would fit PREDATORS but
would need a 5/8" high 5 1/8" carb neck spacer
under each base adapter to lift the base adapters
up this amount for clearance because the predators
have a steel tube hoop across the top of the carb
that sits higher than a holley and it holds the
1/4" stud used to hold the air cleaner
or scoop adapters down.