Hi all, i'm seeking opinions on the different types of valve stem seals.
It seems the current trend is to go with the spring loaded elastomer seals that fit on the top of the valve guide after it has been machined, rather than the old style umbrella seal that was tight on the valve stem and rode up and down with the valve.
It worries me that the spring loaded elastomer seals actually work too well, eliminating oil flow to the valve guides.
I have seen engines,admittedly not Clevelands but i don't see the difference as far as valve guide lubrication is concerned, that have suffered considerable valve guide wear in a short space of time after the fitting of this type of seal in place of the old umbrella seals.
My personal thoughts are the old umbrella seals work perfectly well as long as the guides are in good condition. They allow just that small amount of oil past them to sufficiently lubricate the guides.
I have never come across a problem with oil consumption through the valve guides even on high mileage 351C motors.
Why has there been this shift towards these more positive types of seals ?
What experiences have others had with the spring loaded elastomer seals ?
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