this past week i tought i had melted a piston running 18psi boost and 94 oct fuel, took the motor out and it turns out i have an intake valve that decided to have a keeper come out. the keeper was halfway in but didnt fall, the other keeper was still in place. the result was that the valve wasent closing properly and i didnt have compression on that cylinder. is this a common thing? are the valve springs weak? motor has 127hrs.