Look
http://img410.imageshack.us/my.php?i...lm70m73yr8.jpg
M40/M43/M70/M73 Camshaft alingment tool, aligns and holds camshafts in place when assembling timing chain. Includes the blocks and locking pin (not shown here). To properly secure and align the cam and crankshaft during R&R of cylinder head assemblies of a.m. engines.
i bought one as well for my M40. and frankly I don't understand its usefulness.
when doing the belt, we set timing marks and double checked with a screwdriver through a spark plug hole.
we didn't open the valve cover.
i tried the tool on a spare head and all it does is locking the camshaft. blah.