Unfortunately, when you buy a new carburetor you also need to become an expert in calibrating said carburetor. They are typically far from the mark when they come out of the box. Luckily the 1409 is about the easiest to set up, but you will need to read the entire manual from Edelbrock and understand how that carburetor works and then go to checking the jetting, springs and needles by virtue of a systematic process. Start at idle, work into cracked op, then midrange and last wide open. Any changes made to lesser throttle plate openings effect the greater. So start at the bottom and work up. Unless you own an air fuel mixture meter you will need to pull your plugs a lot after runs of 10 or 15 minutes.
