well now i was also wondering about the keepers coming off . when i first got her she had several of them off and thats how the valve got bent and two other guides were popping up and down . just gotta find the time to pull the intake and check both . i know it's not the bottom end as it carries way to good 'a' oil pressure for sloopy enough tolerances to let one spin { bearing } . like i said before my estimates range from a couple to purty high , but you wanna play ya gotta pay , and i like being the only fool in town driving his flatty daily !!!!!!!!!!!