Do you really need to lock the crank with that special tool (the locking bolt thing)?

Seems to me... if it's just a clearance check then it's no big deal with the crank moves a little, unless you have to take the cams out.

Only for check no, but you can make one easily.

First of all sorry because my english is so poor and I dont know the name of a lot mechanical tools and devices.

You can buy a 500 mm rod bar (not sure if its M8 or M10, take a look to the mechanic book to be shure) and 2 rod nuts.

Insert the bar into the hole to block the crankshaft and the insert the 2 nuts i to the bar (one against another) to block them.

Do the same than the special tool but is cheaper.

Special tool is cheap also. And it will give you peace of mind.

0113 080802 Crankshaft locking bolt

Search for my first 990 valve adjustment post

If you decide to do the tool yourself, a 80mm bolt with a 1,25 thread rise is ok - just do a 30 degree angle at the end of it and make the threads loose by filing the reads edges down slightly and going through a couple of times with m8 x 1,25 die... By so means it doesn't cut anything off the engine casting and doesn't push those chips into the crankcase...

I've done it without - which is no problem as long as you are careful. Each cam has a line on it so easy to get into the correct position. Also you can loosen the cam bridge bolts and recheck your position before removing. There is a risk the crank will move and I wouldn't leave it for any length of time without the cams in eg waiting for shims. Best to put cams back in and lightly bolt.