Holley Tuning Help

Bob, I will try this test to see if I can cure the bog issue. Cracked, I was reading about these 10* and 14* bushings on another thread. Be easy on me as I am new to this but would these replace the black bushing I have in the distributor now?

Is my current black bushing limiting me to 18* mechanical or advanced? I understand that I need to get the timing where the car wants it before I worry too much about tuning the carb. I guess I just don't understand exactly what the 10* and 14* bushing do, but if these will make my car run better you can bet your *** I will be buying them from you!!!

Thanks for all the help!