Valve guides with no seals

[kaysystems]

I disassembled my large valve 250 narrowcase cylinder head, but notice that the valve guides do not have seals, The top of the guide is tapered almost to a knife edge. They don't appear to be worn.
When were these used? Was it a racing mod?

Jus wondering if I should replace the guides with ones for a seal.

Thanks

David

[graeme]

Is there any O ring inside the top of the guide ?

[ranton_rambler]

My 175 has no valve guide seals.
Nor does my Guzzi 850 for that matter.
Ian

[veloduke]

If there's no need to replace the guides, i.e. no wear and no smokey exhaust, then I would leave well alone and use as is.
I have heard of machining a knife edge on the guides, to scrape excess oil off the valve stem, but does it make a dfference?
I have run engines with no seals and no smokey exhaust due to oil leakage.

[blethermaskite]

I don't think any of the earlier singles had valve guide oil seals (could be wrong ) certainly any of my older ducati's didn't have them, and I think they were knife edged in the valve pocket. knife edging a valve guide is meant to act as a scraper. As all have said unless your guides are worn they will be fine without seals (in my experience).
Cheers, George

[kaysystems]

Is there any O ring inside the top of the guide ?

No o'ring

David

[kaysystems]

Thanks to all. I certainly prefer to leave things alone. I don't detect any play.

David

[ranton_rambler]

In the Guzzi world, the widsom seems to be that adding seals can lead to more rapid wear, as there is no oil finding its way between guide and stem to lubricate them. Could be an old wives' tale....

Ian

[Jordan]

Over oiling of a running engine through a valve guide only affects the inlet valve, which is subjected to vacuum.
An exhaust valve in that case does not tend to suck oil like the inlet when running, but it might help to have a seal or something to prevent oil from dripping down the guide after the engine is stopped - causing a brief smoky startup next time.

[Nick]

Triumphs don't use seals either.