Need help, been here before about the carbs. 1957 Chevy 3200, 6” 230 straight 6 ( think motor from mids 60’s C-10) engine has dual single carbs. Both professional rebuilt last month. Carbs set 1 1/2 turns Crank and idle perfect Once I am on the road they flutter and I have to feather the gas to get it moving. I purchased the elderbrock uni sync tool to help tune. When I put the tool on front carb I had to tighten the center almost closed to get the ball up. Move that setting to back carb and it pegs out the float and bogs engine. So I flopped the tool and set off the back carb and moved to front, couldn’t get the float to move. I am at a loss, i know engine is old and needs a rebuild, would this be the problem? Hear a little click under valve cover, could setting valve clearance help? I am not a mechanic, so I ask stupid questions.
I'd start by removing carbs. Put a little grease on each side of the gasket and reassemble. Does either carb have a choke?
I see now, dual manual chokes. So the carb adjusting and test drives are with the engine at full operating temperature and both chokes fully open? One carb has a vacuum line to the distributor vacuum advance and the vacuum port on the other carb is plugged?
I had to take my Uni-sync apart and drill out the small holes, it wasn't made very well and took way to much vacuum to lift the float. My engine is a 250 with dual carbs, and neither would lift the float on the gauge till I worked on it. With that said, your idle adjustments are not even. Slow the back one down and speed the front one up till both register the same on the sync tool. You may have to speed up the idle to get the air speed up, once both are equal, return to normal idle speed backing each one out, a little at time, jumping from one to the other. Your goal is to have both throttle blades in the same spot and each carb delivering 1/2 of the air the engine needs. As it is now, the front of the motor is running lean.
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