400 barrel 'O' rings

[Matt_Harrington]

Do the large 'o' rings that go between the barrels and the upper crankcase move into position when the barrels / head are snugged down - I ask as I can't see a way of keeping them in their grooves.

[Trigger]

It slips over the outside of the bore liners. Wipe red rubber grease over the o'ring to stop it folding when you roll it down the liners . It just needs to sit up against the grooves and will go in once you torque down the head 

[McCabe-Thiele (Ted)]

When I fitted mine I put Red Rubber grease on the rings plus some in the recess at the top of the liners as per NJ's advice. When I pushed the rubbers up the liner they stayed in place much like a carb bowl one does.

[Matt_Harrington]

Cheers! red rubber grease at the ready!

[McCabe-Thiele (Ted)]

I often wondered why there are O rings as well as a base gasket.
Only time I have encountered something  similar was on the old Renault's that had wet liners.

Someone here will know the reason no doubt.

[Matt_Harrington]

Especially as the liner goes into a non circular aperture in the top crankcase.....

[Bryanj]

I was told it was to stop oil "wicking" up between liner and block

[Trigger]

Especially as the liner goes into a non circular aperture in the top crankcase.....

They should seal against the base gasket 

[Matt_Harrington]

Perhaps I'm just over thinking things. I suppose there is enough of the top face of the crankcase to push up the 'o' ring and the rest of the ring will follow suit. The gasket appear to only have about 2/3rd of the gasket that will touch the 'o' ring.