A Core deposit is a form of deposit you pay until returning your old part. If you don't have the core at the time of purchase, you must pay the core charge. That charge is refunded to you when you return the core.
Haynes Weber Carburetor Manual
These Haynes Techbook Weber carburetor manuals offer detailed instructions and procedures for overhauling and tuning Weber carburetors. They also include information on Zenith Stromberg and SU model carburetors as well.