Need help setting timing and carb

on a 318, even with a mild cam, set it at about 10-14 deg. advanced for initial timing. 20 will put alot of strain on your starter and is too advanced for your engine. the carb is the last thing to get tuned. for your idle mix screws, with an rpm gauge or vacuum gauge, get the highest reading, then in 1/4 to 1/2 turn without dropping reading. then lastly set idle speed.