beefing up my 318???

I do believe the engine was rebuilt, i can start it up on the first crank and drive daily if i want to, but the car doesnt have much pep to have fun with. So thats why i was thinking maybe it needs a tune or to adjust the timing. The car has dula exhaust and i believe headers, and a cam but not sure the specs and has a 4 barrel carb on a stock intake. the car drives fine but doesnt have alot of power.