Fourbrads: I had the exact same problem with my rochester b carb. Mine was so solid that I didn't believe that it could possibly come out. After failed attempts with PB Blaster and WD 40 and vise grips, I finally grabbed my wifes' hair dryer, putting heat on the piston and surrounding area. After putting some heat on it I put the end of the piston into my bench vise and slowly started twisting the carb back and forth (keep a hold on the carb so you don't break the piston). The piston finally started rotating back and forth and I slowly twisted the carb until I worked the piston out. After cleaning the hole I pulled the spring out and started the rebuild. The piston know moves very freely with the same spring. Good luck!
