I have wondered about that. I still have my pump. Just spent all day putting 1200 carbs on. BUST!!!! I finally got it synced and got rid of of the hunting for idle issues by plugging the vacuum tube to #4 carb. The carbs looked good except for the idle screw for #4. It was eaten away with corrosion. Didn't have another so, why not??? I got back from the first run, pretty good take off but sputtering at above 3k. Pull back not the garage to start on the car and I felt something in my shoe. I take it out and it's a small spring. Hmmmm looks a lot like a spring from the idle screws. Did I screw up? Moi? I go to check if I forgot the spring. Get to carb #4 and it is empty, no screw, no spring, no washer. So, I'm screwed, errrr not screwed. I think I have another one 110 miles from here. I think I liked the 1000 carbs better, but it isn't fair to compare until I get a set in there that is set up correctly. I might try swapping my #2 carb from my 77 set tomorrow, the one that doesn't leak.