I have a 1972 240Z with the SU carbs. These carbs have the oil reservoir for what I call the dashpot needle piston. My problem is that when I try to fill the reservoir, the oil leaks into the air/fuel mixture which burns through the cylinder. The oil reservoir cannot maintain the seal for the piston. Obviously, I need to rebuild the carbs. My question is: Is it better to invest in a set of Weber carburetors or to rebuild the SU's?

In my opinion you would be better off rebuilding the SU's. Webers are OK but the can be a pain to tune, not to mention the are expensive. Webers are probably more than you need for an L-24 unless you plan on doing some serious engine work, they don't work well on a stock engine.

Take a look at www.ztherapy.com, they have anything you need from rebuild kits to completely restored SU's. In the long run you will still save money over the Webers.