Distinctive start behaviour 2.4i

Hello, the speed at my V50 (2.4i with 170 hp) is immediately after the cold start about 20-30 sec. at about 1,800 rpm. This is so far OK, and also known from other cars. But the engine is quite noisy. Is the engine at operating temperature it can happen at start ups that the valves briefly clearly audible clapping (can of course be something else, but sounds like valve clapping). Is this normal or does someone have the same symptone with his Volvo ? Greeting