slice with wood (but not with iron)

I manage to hit my irons pretty straight and far
(140 to 150 metres with I 6)

but with a 3 wood, I can't hit straight, I've always a big slice to the right

when it goes straight it usually also goes far (or not?): about 180 metres

how to solve this ??

the obvious answer is that a 3 wood is longer and harder to control. A slice happens from an outside inside club path with an open face. Without seeing your swing will not be able to tell what you are doing. However, your tempo may be different with a 3 wood because you are trying to hit it farther, creating a disconnect between the arms and the body. There are 2 things you can try
1) choke up on the 3 wood for more control and try and swing to hit the 150 marker at the range. This may get your feel for tempo back again
2) Place a head cover under the left armpit during the swing. Should only fall out at the very end. will help maintain the arm-body connection.

I did some practice at noon with the 3 and 7 wood

and I managed to get rid of the slice

What I changed is the clubface in relation to the ball
Since I put the ball more to the left with a wood, the contact is different and the clubface should be different I guess

anyway what I did is put the clubface square to the ball; move the club to the center of my stance (and then I have a closed clubface), backswing, downswing, and the ball went straight and about 200 meters

maybe all this is not like it should be, but it worked !!

center of the stance for a 3 wood, this is just a band aid and will fail you. You need to put the ball up and fix the problem, just my opinion though

I'll try to post a video; that should make things clearer

center of the stance: I mean that the clubface is in the center, not the shaft (which is to the left); I keep the shaft in line with my left arm, wrist and hand and my right arm and wrist is in a hook

I see what you are saying, balll is still up but club is a few inches behind it. Scratch my initial comments, moe norman did it kind of like this

that's indeed what I meant

And I also focus my eyes, not on the ball but on the empty spot in the middle of my stance, and then just let the club swing through and listen to the beautiful sound of the club hitting the ball

I als must add that this was on driving range on a mat and whithout teeing up