A few months ago, my engine developed a valve lifter noise which begins about a minute after a cold to warm start. It sounds like a single moderately noisy tapping sound. This goes on for a minute or so until several other valves erratically join in. Once the engine is fully warmed, all the valve noises go away. I use Mann oil filters and faithfully have the oil changed every 5000 miles. The cylinder head is a used replacement installed 8000 miles ago after the timing belt tensioner failed. The noise developed about 4000 miles after the head was replaced. Car has 193,000 miles and other wise runs well. Any clues as to the cause and fix of the valve noise?