First up, The annoying cam chain rattle @3000 rpm. Car history suggests the engine had been renewed after about 150,000 miles ( now on 230,000 ).
Now for all you M42 gurus this would suggest differences in timing gear, something I was unaware of
When I whipped the timing covers off and realised there is no idler gear, just another chain guide the light bulb moment occured and then the sinking feeling, I've already got the parts for an early engine
First thing that I noticed is different is the bottom chain guide that sits underneath the crank sprocket.

Wider and the mounting holes are in different places (Incorrect replacement is the top one)






















































