valve stem seals

[Matty]

Im currently rebuilding my 850 cylinder head, and Ive noticed that the stem seals are O ring looking things, instead of the type that fit on the valve guide. I need to replace these seals as they have perished, but what I need to know is the order of assembly?

Is it possible to fit the seal then slide the spring and top cap of the seal without damaging it? Or do you have to compress the spring and fit it just before the collets?

Cheers
Matt

[littler]

to be honest i wouldnt bother!!

if you have fitted new guides just use the normal type.

the o ring ones do not do a thing.

[Matty]

I did wonder about how well they work, considering there position on the valve.

Im using the original guides, as they look in good condition. Do the standard seals fit over the original guides, as they don't have a retianing groove on the top?

[andy1071]

I believe the idea of the 'O' ring type seals is that they seal against the top of the valve guide at full valve lift, but let a small amount of oil down the guide at part lift to lubricate it. But like Littler, I would fit the normal type.

-Are the guides the unleaded 'silicon-bronze' type? -If not, maybe now would be a good time to fit them?
Not too sure about the durability of iron valve guides with normal type seals and unleaded petrol....