912 valve stem seals

[dcraigmyle]

I am having my heads rebuilt . Did porsche fit valve stem seals as standard on the 912 engine.
David

[Ashley James]

They did and I think PRS told me not to bother with them on my SC.

[dcraigmyle]

Thanks
Max at revival thought it was just to the intake valves.
David

[912uk]

Andy Prill from memory didn't fit them as the tollerance on the heads he refurbed for me didn't need them..
now this was some years back and I can't 100% recall if it's intake only or exhause only but I feel confident that with refurbed heads from him.. they where not used anymore. Call Andy or Graham Ex Rogers Bray guy.

[Kneeslider]

I might be wrong, but I've never seen valve stem seals fitted to exhaust valves. If you think about it, there's no point. There is always positive pressure in the exhaust tract compared to the rocker box, and that would mean that oil never gets down the exhaust valve guide.

[neilbardsley]

I might be wrong, but I've never seen valve stem seals fitted to exhaust valves. If you think about it, there's no point. There is always positive pressure in the exhaust tract compared to the rocker box, and that would mean that oil never gets down the exhaust valve guide.

Can you explain what you mean? I thought the pressure was in both direction in the exhaust during different parts of the 4 stroke

PS The folks on the registry agree with you

http://forum.porsche356registry.org/vie ... st#p187821