[Rick Parker]

I did this but as I recall the secondary (rear) bowl had the initial casting provision for the diaphram (both bowls are initially the same before machining). I had to use the Main body and metering blocks, and throttle base plate for a Double Pumper. I then drilled the passage in the rear bowl leading from the pump cavity to the metering block and intersected it with one of the two holes drilled in the pump cavity floor. Then put the little red rubber "Mushroom" check valve, threaded the 4 holes for the diaphram cover and that was it. Then you end up with a single 4bbl that most efficient air filters will not fit because the carb is too long!