gtb2006

I just rebuilt the carbs and started with them both 2 full turns down, but after the above difficulties moved them both to 1.5 turns based on the service manual.

My l24 with SU carbs is up and running but I’m having trouble with the air fuel adjustment. I adjusted timing to 5 BDTC and balanced the carbs using a synchrometer. Idle is around 750 rpm. When I use the piston lifter on the front carb rpms increase and then come back down but the engine will then die if I don’t let the piston drop. When I use the piston lifter on the rear carb rpms increase, stay increased (around 1300rpm) and the car backfires. When using the piston lifters ideally rpms will increase and then drop back down without the car dying correct? It seems like the front carb is a bit lean and the rear carb is rich but they are supposed to be adjusted together correct?

I’m rebuilding my round top SU carbs on my 1971 240z and after everything was cleaned and put back together one of the pistons keeps binding in the dash pot when the top is screwed down. I’ve switched tops and the same thing happens. The jet and needle don’t bind at all and the piston slides freely with the top not screwed down. I’ve tried tightening the screws gradually and making sure the piston slides freely as I go but every time the screws are fully tightened the piston gets stuck and won’t fully drop. Any suggestions? Do the screws need to be fully tightened for the carb to function or can they be snug without causing issue? The carbs are 4 screw tops.