If the carb is in good condition then start with a vacume guage! After vacume range has been established then check power valve to make sure it is proper for your application! I have been told that you need to be at least 2 inches lower on the power valve then your lowest vacume reading at an idle! Check you idle screws they should be some where around 1.25 to 1.75 turns out from fully closed. With this all proper the next thing would be to start checking jetting. I like to do primary first, which means staying out of the secondaries while tuning. When you get the primarys good then you can open the secondaries & continue there! Also recommend using a new set of plugs while doing this.