Hooking Up Dual Carb Throttle Linkage To SC520 STREETCATCHER Butterflies
Instructions Below Photographs
Setup your sideways linkage as per the above photographs.
1 Remove the #27 inside black arm attached to the barrel valve (The Scoop is supplied this way) and keep it as a spare. This arm will be correct if you ever use the scoop on dual inline 4160 carbs, or sell the scoop to someone for this application. (If you do, this setup is different and you will need to invert the barrel valve, buy an additional male rod end and just join the two rod ends together to connect the barrel valve shaft and the butterfly shaft to each other, then run a long link from the bottom of the rear carburetor linkage to the inside #27 arm which will be hanging down and pushed to open the butterflies.)

2 Replace it with the #25 arm supplied in your sideways linkage and set its position close to the left photograph above, notice when the linkage is set up correctly the top ‘rod end’ will be right up within an 1/8" of touching the scoop body.

3 Remove the front existing arm that pulls the throttle on your front carb off of your existing dual carburetor sideways linkage and slide the #23 arm onto the splined shaft and just onto the unsplined area and locate it approximately as shown in the photograph.

4 Connect the two arms with the ‘rod end/link’ assembly, with spacer at the top and with the bend in the threaded rod at the bottom, re the photograph, this linkage has a center to center length of 4 ½” (107mm) if you ever dismantle it.

5 IMPORTANT: Make sure the top #25 arm and link connection does not straighten out fully before reaching wide open throttle resulting in the linkage stopping the carburetors from attaining full throttle and, excessively pulling down on the barrel valve which could break the arms.

6 Once you have your linkage arms in the right positions and the throttle fully opening you may have to loosen the set screws on the lower dummy barrel valve arms to position your butterflies to sit slightly ‘out’ at the bottom at idle like a real injector does and to obtain a wide open throttle butterfly position.