Need Help - Knocking Noise - 65 Series 2a SWB Petrol

Hey everyone, need some expert help. My series 2a has started making a terrible knocking noise.

Here is a video (not mine) of the same noise and same conditions.
https://youtube.com/clip/Ugkx1a68wuD...S4_KfEwMVnQ0-8

He found the head gasket to be the issue but that doesn't appear to be my issue. So far I have replaced the head gasket, cleaned the cylinder head and piston faces, reset clearances on all tappets, new spark plugs and checked gaps.

The truck starts and idles fine/smoothly. Noise only happens when engine is under load. Noise is the same regardless of engine temp. Feels/sounds like it is in the back end of the engine.

Would appreciate any insight anyone has.

Possible broken crankshaft or a bad connecting rod comes to mind. Possible dropped valve head??

Sounds like something vibrating to me, transfer lever or a heat shield ?

thrust washer someplace, or something in the bell housing. remove the drain plug on the bell and measure the end play on the flywheel or same on front of C shaft. if it's a real tinny issue probably something external but on the video the guy was talking all the time!

It could be your wife trying to get into the garage... ;)

In all sincerity, it could be pinging. Your timing may be too far advanced, or your advance mechanism is too aggressive (never seen this though - unless its the wrong distributor). Your valve lash may also need adjusting - which would also sound worse under too advanced timing as they bang shut. Or finally, you may have valve seat regression.

what's the oil pressure like? mine does this and it needs new inserts so it waits for a rebuild. your sounds a bit tinny, not exactly a hard knock, at least on the audio.
if you have 50-60 psi oil your engine is prob ok, you could put some lucas oil treatment in it, that saved my dozer engine!!
other than that, biffidum could be tracking on this.

Disconnect vacuum advance and drive. If noise is reduced under load - bingo. If not, check valves. Valve adjustment nuts should all show similar thread counts, if one has significantly more thread you have a worn valve seat.

welll, ya, it does sound kinda like valves ...... but that doesn't happen overnight......... did you change gas type or torque the head or anything that'd affect valve train?