I replaced the oil pump recently, and dramatically restored the oil pressure to specification. However, coinciding with that the oil consumption has now increased a little, and I have noticed that two of the plugs tend to get a bit oily. There is no visible smoke, but I notice the change because previously the engine consumed no oil at all and the plugs would last 10,000 miles and still look new.
So my theory is that with a much better oil flow to the top of the engine, a bit is finding its way past the valve guides on 2 cylinders.
The engine runs like new, and there is very little valve noise. However, it is coming up to 300,000 miles, when the timing belt is due for renewal, so that would make a convenient point to replace the inlet valve oil seals. I have experimented on a spare B21 head and successfully compressed the spring and extracted the two collets with a screw-driver and a magnet, having locked the valve from the underneath, using a made-up tool.
It therefore seems feasible to do the job with the head in place, using the rope-trick.
Has anyone done this? Are there any snags extracting and replacing the seals?
Also I wonder about oil drainage. The oil has been changed every 3000 miles, and inside the camshaft cover looks bright with no evidence of sludge. I have looked carefully on the B21 head and can see no hidden drainage holes other than the wide ones leading into the main drainage chamber. When I add new oil it runs down into the sump in seconds, so there appears to be no blockage .
I wouldn’t normally bother with this degree of pampering, except that the engine was in such pristine condition before the new pump, and I don’t want to poison the catalyst with even a trace of oil smoke.
Any help or observations gratefully received.

Cliff Pope