I'ev never had one I couldn't tune. Some people give up. Some people don't like not throwing more fuel on it. I've had bad carbs from Demon/BG, Holley, Edelbrock, and Carter. They could all be tuned into good performers when the time and knowledge were applied. It sounds to me like you need to first examine the timing curve and setup on that engine. If it's totally stock... Does it have points? If so, you start with setting point dwell. Then set initial timing, then seet total timing, then tune the carb for idle quality and speed, then get the strip kit and tune for drivability. If you don't go in that order, you've got a good chance of getting PO'd and giving up because you WILL have to go back and fix what was overlooked. Holleys run well because they throw fuel at everything until it runs good. Or feels like it to the driver. "Well Tuned" doesn't care who made the carb.