The lower groove is for the O ring seal, which is installed on the valve stem after the spring is compressed, then the keeper fits into the top groove. Release the spring tension VERY slowly to avoid dislodging the O ring as the spring retainer slides over it. I oil the rings a little as I install them.

Just a word of caution- - - -if you choose to use a positive stem seal or an umbrella seal instead of the O ring, DO NOT install the O ring as well. The valve guide needs a very slight amount of lubrication, and totally stopping oil flow down the guide will result in rapid valve stem and guide wear. I've seen guides with over 1/16" of clearance around the valve stems after running a while with both types of seals installed. Those engines used oil by the gallon!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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