Cam chain/Cam alignment

[Shiny]

 :falldown:


So long story short, I am nearly finished with swapping the cylinder head on my 86 K75. I got to the part in the reassembly where I have to mesh the cam sprockets with the timing chain, but I'm confused about the alignment of the cam sprocket marks. The only way the cam lobes don't press on any of the valve lifters is if the sprocket marks are pointing down, but Clymer's indicates that the marks should both face up in one step, and then towards each other in a different step. Obviously these cant't all be true.


Piston 3 (furthest aft) is at top


Tick mark on crank sprocket is at O/T mark


Can anyone help me out?

[Laitch]

The only way the cam lobes don't press on any of the valve lifters is if the sprocket marks are pointing down, but Clymer's indicates that the marks should both face up in one step, and then towards each other in a different step.

When the camshafts are installed and bolted up, the sprockets aren't attached, so I think you might be misinterpreting an instruction and consequently are ahead of yourself. Not having the lobes pressing on the buckets is to reduce bolt up stressing when you are installing the camshafts. After the camshafts are bolted up, the sprockets are installed and all alignment is brought into agreement.

Sometimes consulting a different reference clears off the fog. Attached are a portion of the instructions from the BMW manual that is available here in the Technical Library. It might help clarify where you are in this process. Align the sprocket marks parallel to the head seam and aimed at the intake side of the engine. Keep your crank mark aligned. When you install the chain, you can put a wrench on the camshaft flats to help hold alignment.

Camsprockets from BMW manual p.11-80.0.jpg (38.82 kB . 580x576 - viewed 299 times)

I think you should download that manual from here. You're getting close.

[Shiny]

Yup, that's definitely the piece that was missing. Clymer's isn't exactly clear that the sprockets need to be removed from the cam shaft for reinstallation, just that they can be removed for inspection.


Thanks Laitch!