I have done the dual jet swap that efi-diy talks about on my 78 nova with a stock 250 engine and a turbo 350 trans, also stock. Over the decades I have done a few carb swaps, this has to be the best swap I have ever done! Let me share some pointers that I learned along the way. 1. Get the air cleaner from a car of truck that has one of these carbs, the opening for the carb is special and no other air cleaner will fit that I know of.
2.there are 2 sizes of this carb made, the throttle blades are the same size at 1-3/8 but 2 different Venturi sizes 1-3/32 and 1-7/32. Be sure and get the bigger one. The bigger one will flow about 300 cfm (at 3.0 hg that 2 bbl carbs are rated at)
3. To my knowledge there are no carb adapters made that will fit this carb, I had to have one made but it sure was worth it! The ease of starting, throttle response and drive ability difference is night and day. I would recommend that you get a carb for a 79 305 Carprice. That will get you the big one and get you close on jetting because the engines are the about the same size. If anyone else has done this swap I’d like to know about it so I could learn. Hope this helps. Jay
