valve rubber ring dilema

[davew1949]

I have just done a de-coke and am confused about the small rubber rings in the gasket set. In some books these are referred to as oil seals or in others as packing rings. Some diagrams seem to leave them out altogether. Some texts says they should be sitting at the bottom of the cotter groove, other text says at the top of the valve guides. I've slipped them over the valves, but to be honest they don't look as though they do anything, just sitting forlornly in the middle of the valve stem. They certainly don't look as though they would stop any oil from trickling down the guides. Are they really needed in the later 1098 engines or just a left-over from an earlier design?

I am also planning to take BMC's oft given advice and set the exhaust valve clearances to 15 thou. I'm sure I know but, just to be on the safe side, can someone confirm the order of valves from the front of the engine.

Many thanks,

Dave

[chrisryder]

Valve order from front (or rear for that matter) - E I I E E I I E

You don't need valve stem seals on the exhaust valve either. A small amount of oil running down helps lubricate them, and it won't draw oil in down there like the inlets would.

I can't help with the o-ring things. I've always gone for the later 'top hat' type. Much more effective! Apparently the o-ring's don't last long anyway. If you can wait, try and source the top-hat seals. Again, you only need 4.

[rayofleamington]

Seconded - the o-rings are only of any use on the inlets and these days the materials used are so poor, they split and can fall off the valve stem.
Even when in place, their functionality is not as good at the cupped-style seal, however they are better than nothing. The other end of the valve guide is at low pressure (max suction) when the valve is fully open, so the o-ring should help to limit the amount of oil that can be sucked down the valve guide.

[davew1949]

Many thanks for such a quick response guys.
Dave

[bmcecosse]

The O rings go at the foot of the cotter groove - any 'book' that says otherwise is best put in the bin. Top hat seals are better -but will only reliably stay in place if you fit new guides with a location groove around near the top.