Chevy 350 motor with a two barrel carb on it i changed to four do you ned change the camshaft also?

No, you generally don't *need* to change the camshaft when swapping from a two-barrel to a four-barrel carburetor on a Chevy 350. The camshaft's primary role is to control valve timing, which isn't directly affected by the carburetor's size. The carburetor simply controls the amount of fuel and air entering the engine.

However, if the engine's performance is underwhelming after the swap, *then* you might consider a camshaft change. A four-barrel carburetor allows for a greater potential airflow and fuel delivery, and a more aggressive camshaft might be beneficial to fully utilize that increased potential. A more aggressive cam would improve power, but it could also lead to reduced low-end torque and potentially other changes in the engine's characteristics.

In short: The carb swap doesn't require a camshaft change, but a different cam might be *desirable* to optimize performance if you're looking for significant power gains.