Reply To: Valve Stem Seals

[BernieParticipant]

Nigel,

The original, square section ring vss are designed to stay in a fixed position on the stem and move with the valve, the theory being that oil running down the valve stem is diverted away from the stem at that point.  The “umbrella” type is designed to stay in place on the guide and “wipe” the valve stem as it reciprocates. The latter is likely to be more efficient on an old engine with heavy wear on the valve stems/guides but could possible impair valve stem lubrication on a new, tight, assembly.

I have only ever used the original type square section rings and have never had a smoke problem with a rebuilt engine but, in light of  Phil’s positive experience, I think the umbrellas are probably equally good.

As your smoking has apparently decreased, perhaps it was simply a function of pistons, ringing and liners all bedding in.

B…..