Often the valve absorbers are noisy. Those would be a standard change-out part whenever the camshaft is removed (but maybe they weren't changed out).

Other possibilities are a slight crack in the exhaust manifold gasket. One of them, I mean. These can make a ticking noise, generally noisier on acceleration.

Other than that, some 240s have an engine tick, and that is just the way it goes. I have chased that noise in several cars, to great extent, and with no luck. For some demanding customers who finally gave up too... and drove forever with that very noise. (Including my most demanding customer... me).
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