I have a 230CI Chevy 6 cylinder engine in a 1957 Willys FC 170. It does not have the original harmonic balancer on it, and there is no guage to time against if there were a mark. I have timed it by ear by taking it to advanced till it runs bad, back to restricted till it runs bad, and gone for a happy medium. It seems to run well, but overheats when dirving on the highway. Any ideas on how to time it better, and what I can do to get to run cooler and smoother?