***Does the engine deck lid have to come off?***

Most of the guy leave the engine cover on. I left mine on when I changed belts. It would make things a lot easier but probably isn't worth the extra effort.

 

It would help if you told us what model Ferrari you have... or at least fill it out in your profile.

 

I leave mine on the ol'e Testsarossa...since the engine drops out the bottom of the car. It does get in the way a little...but not too bad.

 

I don't know which car you have (not in your profile) but if a 308 or 328 I think you could do it with the lid on. I would definitely recommend removing it because you have to remove the cam covers to see the timing marks and it makes sense to do the valve timing while you have the covers off. This is a real stretch if the engine cover is still in place. It takes two people to lift it off and makes the job much easier.

 

If it's just belts (on a 308) and you intend to use the external timing marks you can leave it on. If you are doing valve shins at the same time or using the internal timing marks, or timing with a degree wheel, removing it makes the job much much easier, so I remove it. It's about 5-10 minutes to get it off, mayby 20 to put it back on. You save the time back just removing the valve cover because you can see and reach all the nuts. I usually end up man-handling it on and off by myself, but it's hard...3 people make the job a lot easier with much less chance of dinged paint (my paint already s*cks so I don't worry an awful lot about that).