Yes they do and I have used front metering blocks I could use, but as strange as it might sound, I don't want to change the carbs too far from what they are. If changing to front metering blocks, power valves, rear metering blocks, jets, ground secondary cams, etc. It seems I would be better off just getting carbs designed that way instead of turning them into something they aren't. No reinventing the wheel. I just want to tune out the stumble. I have no issues drilling and tapping bleed ports and making different size jets, if I knew more about the circuits. But beyond that, I would like to keep as stock as possible