First I need help finding out with demon carb that I have? I can not find any part numbers on it? I think it is a Speed Demon 650 with Vacuum Secondaries but I am not sure. I have always had edelbrock carbs so if some one can give detailed instruction and how to tune this carb it would be great. I think I have it tuned pretty good, only a slight stumble under hard acceleration. It is on a ZZ4 motor. Thanks

Did the carb come with the motor? If so, go HERE (http://www.barrygrant.com/demon/default.aspx?page=13) for the part number.

HERE (http://www.barrygrant.com/fromBarryGrant/Demon%20Instruction%20Manuals/Crate%20Engine%20Demon%20Manual-06.pdf) is your tuning manual from Barry Grant.