base timing?

have a 1977 280z just rebuilt the motor and trying to get things set right. wanted to know if I need to short something out to get the base timing? Also get it running good and the idle were we want it and then I turn it off and restart it my idle jumps to 1500 to 2000 once or twice if I bump the gas hard the idle goes to where we want it. just hoping someone might be able to point me in the right way to solve it