Hi, Im in the process of putting my XU10J4RS back together, im not convinced i have got the big end caps on the right way round. Unfortunatly i dont have a haynes for the 306.

The one for the 405 tho says the following about the XU Series Big Ends: Note that the faces with
the identification marks must match (which
means that the bearing shell locating tabs
abut each other).

But on my engine it the ID Marks are on the other side of the cap, so its one or the other, not both!

Can anyone confirm how the bearings are supposed to sit in relation to each other?

There is a mark on each piston to show which way the piston faces exhaust/inlet side can't remember which way this is so I'll leave someone else to say then you will be able to work out whch way your bearings go in. I think the big end bearings will only go in one way as they have a bit poking out the back?