Re: m42 stumbling--cam timing?

["Michel Drainville" <MDrainville@xxxxxxxxxxx>]

Shaun, I removed the head on my M42 last year to replace the profile
gasket, and I can tell you that in order to time the cams, the head doesn't
need to be removed. Only the valve cover and the front upper timing chain
cover.
You can check the cams by yourself. Remove the valve cover, rotate the
crank in its normal rotating direction until you reach TDC on the
compresssion stroke. There is a mark on the crank pulley for TDC. When
positionned, look at the end of each cam, the end toward the back of the
car, you will see a square block of metal which is part of the cam itself.
The top of that square (the flat part if you prefer) should be parrallel to
the block and BOTH cams should have that flat part at the same plane. You
can put a ruler over the two parts to vefify that. If one cam is off
compared to the other, it may be due to the timing chain being loose
(streched with time, mileage). You have the choice of replacing the chain
and sprockets for lots of $$$ or, while one cam is at its position, loosen
the bolts of the second cam sprocket and rotate the cam so it aligns like
it's supposed to. Rotate the crank two revolution, and check again.
The sprockets have no keyway, the holes are slotted, so, big adjustment can
be done.
When I reassembled my head, I did that to compensate for the slack of the
chain. It was not that big though.
Go get a Haynes manual for $10. They talk about the alignment of the cams.

Hope this helps

Michel Drainville
91 318ic [soon to be turbo :-) ]
www.geocities.com/bmw_318ic