Mystery engine noise

G'day All. Mustards the name.
I have a 59 FC special sedan and her name is Black Betty. I hope that this might help someone else that might run into this problem I had with Betty.

All was well until a noise which sounded like it was coming from the sump. A knocking noise that just about disappeared when the revs were increased but when on idle sounded like she was in her death rattle.
Hmmm.javascript:void(0); Start easy and work your way along. So I started with the harmonic balancer and since I had a new one sitting around changed it out as the rubber was starting to perish. Also checked timing gear all OK there. Removed rocker cover and side plate, so far so good removed sump check all bolts and the oil pump, "nothing to see here move along" as the wallopers would say. Remove the gearbox and BINGO 1 bolt from the flywheel was loose and was catching on just 1 of the spring retainers of the clutch plate. There was just a little shiny metal where the two were hitting each other. I remover all the blots a drilled the heads so once re tightened i could wire the 2 sets together so if they did come loose they won't be able to go far. javascript:void(0); Hopfully this won't happen to anyone else but at least if it does you might be able to use the info here.

Cheers.
Mustard