ok, I just bought a very clean 1990 formula tpi for 600 bucks because it had a "knock" the guy said. Turns out not to be a bottom end noise, I know this because I did a cylinder power balance test. I thought maybe it was a stuck lifter, ran the car with no valv covers on, and they all appeared to be operating just fine. Then I'm thinking bent valve, nope. So now the motor is pulled apart in my garage, I plan on putting a cam in it and what not. But the stock cam has no signs of wear? And the lifters all seem fine. What do I need to look for like a collapsed lifter or something? I don't want to put the motor back together and have it be something else ya know, any sugestions?