Bryan,
Dwell for your engine typically would be 32°-35°, but 30° is alright. I don't know how the dwell angle relates to your point gap of .016"; the dwell angle/point gap relationship is a function of the contour of the distributor cam, and I don't know that anyone has published that information, mostly because no one really cares- if you set the gap properly, the dwell will be satisfactory, and vice-versa. But a 6-cyl distributor at .016-.019 point gap will get you in the range of 30-35 degrees of dwell. Your dwell of 42° is a little high, indicating that the point gap is a little close. A rule of thumb for dwell is 55% of the lobe angle (which is the angle between cam lobe apexes). For a 6-cyl distributor, the lobe angle is 60°; 55% of that is 33°. Allowing ± 2-3 degrees of dwell gives a range of 30-36 degrees. Some manufacturers go up to 38° dwell (6-cyl), but the reality of it is for low-speed engines, even 25-28 degrees is sufficient for reliable ignition system operation. What is important is that you set the timing after any point adjustment: a degree of dwell change gives a degree of timing change: increasing dwell retards timing; reducing dwell advances timing.
The risk with high dwell angle is that the point gap will be lower that optimum, which can lead to excessive arcing and reduced life. The points might also run hotter because of the longer duration of current flow. For longer point life, lower dwell is better. And set the timing after the dwell adjustment.
Harvester
