Nope, stock mechanical. I'm thinking it's this carb i'm using. It's an edelbrock performer 600cfm carb. I've had a couple mechanics try to tune this thing to no avail. The fuel/air screws don't seem to do their job. I hear they are great carbs, but I haven't had good luck with mine. I may try and rebuild the thing or just get a new one, depending on what I find is the problem. Any recommendations on a brand other than edelbrock? What carbs do most guys run with the 340?