Have you performed a valve lash adjustment to factory spec?

Yes, timing can cause knocking but usually when it is too advanced. Timing chain stretch retards the timing; not advancing it.

If your valves were severely out of adjustment, you could get a tapping sound.

Oil pressure depends on a lot of things like temp, oil viscosity, filter, and oil pump condition. Low oil could produce a knocking. Just ask anyone who has driven an older Chrysler low on oil. Same with a Diesel. Too low on oil and lubrication does not get to all necessary components.

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1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge