I have concluded that 235s make lots of noises that will drive you batty and probably don't amount to much. Tiny exhaust leaks that reverberate off sheet metal. Intermittent valvetrain noise that comes and goes without a discernable pattern or easy explanation. Squeaks and squeals and even a chirp sometimes.
This may not be the "right" approach, but I have decided to mostly ignore them if I know my valves are adjusted, my dwell is set, the top end is oiling, oil pressure is good, etc.
