I own a 69 AMX with a 390cid. I just spent quite a bit on building the motor. It was bored .060 over due to rust on the walls. Everything on the top end was replaced. I retained the original crank,rods and heads, they were mildly ported. Big cam,roller tip rockers,pushrods,studs,oil pump, pickup, oil pan,intake, lifters etc....I found this forum and read about losing oil preasure when it warms up. I was told by the machine shop building the motor that the pistons were a custom order, and that all the bearings that were installed would have been a lot cheaper if the motor was a chevy. Which leads me to believe that the motor is at amc spec. What else can I do to prevent this from happening to me. Thank you all for loving the AMX!!!!!