Many Holley Quick Fuel or Demon Double Pumpers come with no choke horn as supplied from the factory however some double pumper carburetors are available with chokes.

If your carburetor has a choke, it needs to be removed for use with SC500 style enclosed carb STREETCATCHERS

This applies to Double Pumpers being used in the SC500 Series 6/8/10/12/14-71 Blower Scoop, also the SC500-177 used on the Holley/Weiand 142/144/174/177 series PowerCharger and Pro-Street superchargers and also the Holley/Weiand 250/256 mid sized blowers.

All you need to do is remove the 'choke horn' housing away from each side of the center boss and vent tubes by milling or cutting carefully with a hacksaw, and clean them up with a file or die grinder.

Cut the bowl vents
HOLLEY, AED, QUICK FUELS: (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).

The 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 the bowls.

DEMONS: On Demons all you need to do is lower the rear vent about 1/4"

Remember 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.

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.