I was going by the info I read about if the carb has that bump in the outer chamber it was a better carb. Cliff sent a kit to me to rebuild and calibrate to my needs . I found a gentleman that has knowledge and has rebuilt many q/jets do mine and so far it seems he has done a good job . I have to recheck my timing and it was recomended that I set it back a few notches from original specs (16 ) btc on the hood lable specs. I'm not real sure where it should be after the cam swap . I have a 76 f/bird w/350 . The cam that I removed had a letter U stamped on the front and I installed a 2157 edelbrock cam kit . If you have any advice on this I'd appreciate your input ! Thanks !