I installed my cooler today and noticed that there is a gap between the cooler and the duct . Am I missing aome kind of seal there?

There's no seal there. The housing should fit tight to the oil cooler. It looks like you have an org. 6 engine shroud which has the oil cooler air duct attached to it.
There's a metal flap that has to fit between the cooler and heads to fit properly.
From what I see in your pic the shroud is bolted down on the cam housing and seams to be tight. Does the bolt holes in the rear of the cooler line up with that part of the shroud or are they higher up also? You may have to loosen up the bolts and get the cooler portion to sit properly before you tighten the rest of the bolts down.
Again , check to make sure that the metal flap fits properly between the cool and head.
I upgraded to a later shroud so I can remove the cooler w/o having to remove the engine shroud. The later shrouds have a separate cooler duct which helps to get to the oil cooler mounting bolts. It's worth looking into if you ever need to change your cooler or seals out. Otherwise the upper part of the engine (carbs/induction) needs to be removed along with the shroud prior to getting to the cooler.

I added some pics for you. You can see the metal flap that I'm talking about on my later (red) shroud which gets covered by a separate cover. The green shroud is an early 911 version and gets a steel oil cooler cover and has no metal flap between the cooler and head. The yellow shroud is a MFI unit but should look like what you have. You can see the metal flap which I'm referring to on the yellow shroud.

The other bolts lines up correctly. I did try to move it ip a bit before bolting it , there is not much room. I can fabricate a seal for that, I just wanted to make sure that I was not musing anything.
I will be on the lookout for metal tin as well.

Thanks Luke .

I just looked over my engine real quick. There's a small gap between the oil cooler/shroud but nothing like yours. I guess a seal of some sort won't hurt.
I've seen one sided sticky rubber/foam seals that usually go around doors and what not at hardware stores. That should work just fine between the shroud and cooler.
What metal tin are you looking for ? or is it the 914-6 engine tins ?

Luke, I meant shroud. If you can shoot me. Pictures if your oil tank mounted, both under the fender and the engine compartment, that would be helpful.

Thanks

Looks to me like the oil cooler tin at the top has been bent slightly down.

The oil cooler was a 911 modified by Rich Johnson.
The gap helped me. I was able to slide the ratchet in ther with an extension to mount the cooler.

I'll take a look but think I need to go take some pics.

I found some older pics of the oil tank installed. Hope this helps you out.

That helps.
Thanks