That's the way the 3 screw carbs were designed. The one with the short ears (left in the pic) is for the rear carb.

Well my mechanic had to drill another hole to obtain the same fuel level on both carbs in order to avoid the car stalling at idle. Strange design. The holes were the needle valves are fastened are also if different depths. I cant believe i paid 700 usd for ztherapy to set up my carbs and i am still dealing with this type of issues of different measurements on float valve compartments

4 hours ago, jalexquijano said:

I cant believe i paid 700 usd for ztherapy to set up my carbs and i am still dealing with this type of issues of different measurements on float valve compartments

I have dealt with Z therapy more than once and their service and products are outstanding!!!!!

Maybe it's operator error?

 I agree with Patcon, .

 Jalex, IMHO, YOU should be the one tuning these carbs. You don't need no freak'in "expert" or even a "mechanic". You'll be glad you learned how.  Let me try to convince you with a trip in my WayBack Machine. 1973, The first thing I worried about when I bought my first Z was the horror stories I'd heard about British cars with SU duel carbs and constantly having to tinker with them. I didn't know anything about them, sooo, I took it to a "sports car garage" for it's first tuneup. $76.00 (a fair amount of money in 1973) later I drove the car home and realized that the tune-up hadn't changed the way it ran, which was good, before and after. I realized that I couldn't afford frequent tune-ups at that price. (Thought it would need them) I bought a Uni-Syn and a repair manual and started cleaning and checking the carbs when I tuned it up. They were always fine. It wasn't until I took a suction chamber off, out of curiosity, that I realized how simple the whole thing was. I already knew about float chambers and had read the tune-up manual. It was the EUREKA MOMENT. There was little to them. Not as complicated as a downdraft carb. To this day I'm amazed at how simple and effective the SU's are and still don't understand where the fear factor came from, unless it was the British aspect. You can do it. Give it a try. All it takes is a balancing gizmo, a screwdriver, a tune-up manual and a beer.