Hi Sixto,

I'm only replying to your post so I get e-mailed when you get answers because I am also interested the answers.

The only answer I know is that the valves will rest on the piston when it is at TDC and you won't have to worry about the valves droping into the cylinder. But you have to rotate the engine to bring other pistons to TDC. This might screw up the timing if you do it with the cam off the engine and the timing chain loose.

P E H