Eric
It may not be just the O ring Depending on the Milage It may very well be the guides. The Umbrellas Work Good. For that Matter a little to good Not letting enough oil to the valve. I have rebuilt heads In the past that have had the Umbrellas Which had Burnt valve stems and chewed up guilds because of the Lack of oil to the guide. If you are plaining to keep It long term and this is a High milaged motor It maybe better to have the Head cleaned up and freshen the guides.
Also You can Use a small dia. string/rope In the Cyl.take off the rockers& remove plugs. Put the string/rope into the spark plug hole and Turn the Motor Over by Hand till it comes to a stop This is top dead. Remove your springs Replace O ring Or install the umbrella. Reinstall springs Rotate the block the Opposite way and Take the string/rope back out reinstall rockers & plug And You will be good to go.
Hope this helps }[oooooo]
God doesn't like ugly.
