Are O rings necessary with Copper HG

[Lextreme II]

Actually right now, the company i deal with made a new copper gasket with build in O-ring. Pretty insteresting. The O-Ring is sandwhiched between the copper.

 

[Red Supra]

With a properly prepped block and head surface and a good multilayer gasket there is no need for o-rings. Look at the Cometic MLS headgaskets.
O-ring seal the combustion chamber really well but sometimes you get coolant seeping down the side of the cylinder head.

 

[Pro]

you could also sleeve the water and oil galleries in the block with matching recesses in the head.

that will eliminate all bypassing.