4-108 valve kit

[phorvati]

Does anyone have an idea of what the purpose is for the black rubber cups with the hole in the middle. They are to be fitted onto valve stem and inside the spring(s), facing down just below the valve collar.

Manual is also talking about inlet valves having seal that looks like a rubber o-ring fitted onto stem. It did not come in a rebuild kit, and it wasn't found to be there during tear-down.

valve kit came with both sets of rings. westerbeke 40(4.108) model had only outer rings. Any recommendations on putting both vs just the outer.

Thanks