Does anyone know if it is possible to remove the timing cover without pulling the head?
You have to remove the studs that go up thru the head, remove the dampener, and drop the pan.
So there is enough room to pull the upper part of the cover away from the studs for it to come off?
Which car? Early ones with a tin gasket are easier. A composite gasket may be harder to remove and especially replace, because the sharp edge of the TC might dig into it on the way back in. The cover must come straight off because it’s pinned to the block with two locating pegs. You may need to untorque the head so it has some give. Also with the head on you can only grab the cover from the bottom, and you don’t want to mar it by sticking metal prying tools in so it’s tricky.
The small 5/16 studs going down and up will need to be backed out with double nuts or a stud remover.
A bit hard to see (as someone would say, can you see me waving my hands?) but I would say no. You have to remove those two studs from the head by double-nutting or some other method.
According to Jaguar tradition there are two locating dowels there, so it will not move downwards before you can pull it forwards enough to clear the dowels.
I did that twice on a 4.2L and it wasn’t too difficult. You need to have the crank in a certain position to get the sump off, and IIRC also 1” spacers under the engine mounts. Once the sump and waterpump and those two studs are out you should be able to wiggle it off. But it needs to move forward first, then it comes loose.
There is a recent thread on #e-type with the same question, he did get it done I think.
I have done it on my Mk2, with good success to change the chains and tensioner. It has a tin gasket and head remained at full tension.
My timing cover was cajoled back into place without damaging gasket etc. As you say a composite gasket may not be rigid/hard enough. I have heard of people putting a small radius on the contacting corner edge to ease the refit. I did not have to resort to this. Note, my car is a 3.4 but unaware of any differences. Paul