James head gasket, which way up?

[1340evo]

I hate things like this, no bloody instruction and no markings.

So going off the ring thickness on both sides, which way up do they go?

Looking on the net I've found two results that say up, and one down for the thick side ...  but I'm thinking thick down??

probably don't matter, but I'm thinking thin side up to give more of a pressure point against the head?

[Burnout]

There is no top or bottom to those gaskets I am aware of.

[1340evo]

Well, they have gone thin side up... I could kind of make that work in my head 

[Burnout]

That metal rim turns into a Bead of sorts that assists with sealing.
The edge of it where it is bent over is what creates the seal "bead",
the tail lengths are inconsequential other than to establish rigidity and get a bite on the composite center.
Different tail lengths would also taper off the additional thickness instead of a square step, with opposing sharp edges that would cut the composite material. (so the length difference is likely on purpose)

It might matter if you were using it with an O-ringed head.

I'm not an engineer but I did sleep at a Holiday Inn Express last night.....

If it mattered there would be a note on the data sheet and/or they would be marked top.

[1340evo]

yup, that was my thoughts... there are in now