Is it a roller cam, with a double roller chain and a mechanical fuel pump?
I had a problem for a little while with a noise that I couldn't track down. Turned out a roller cam moves in and out of the block more than a hydraulic cam, which closes up the gap between the timing chain and arm of the fuel pump. Just enough that there was a witness mark on the arm from the pins in the timing chain. I tweaked the arm in a little at that spot and no issues since.
I know it doesn't answer your question, but thought maybe it would help anyway.
