My car started making a strange noise, kind of a squeeky tick, last week, all of the sudden. It has been consistent, same volume, and is definitely correlated with rpm. Car has been cammed for 70k miles, much highway, adult driven. RCR cam, LS7 lifters, BTR pushrods, trunions.... I pulled the valve covers today and everything looked okay, did not pull the rockers..... Also used a mechanic stethoscope. Definitely not the injectors, but otherwise inconclusive. Pretty sure it's coming from the driver's side. Thoughts? I don't think it's a collapsed lifter, but beyond that....? Could it be a bent pushrod rubbing? Worse would be a lifter failure, but how do those sound? Thanks.