Well there ya go Jerry, that's the kind of answer I was looking for. Pretty much confirms what I suspected about the overlap. Not much you can do to change the ramp on the cam so they had to find another way to keep the primary closed a little longer.
Ya got me thinkin bout the time period for coil saturation. You say the ideal coil saturation point is 66%, but wouldn't that vary according to the rpm? 66% at 500 revs is going to be a lot longer time period than 66% at 5000 rpm, isn't it?
I’m also wondering about the point gap. We were talking about a Chevy 6 banger here correct? Closing the point gap increases the dwell angle of course, so theoretically speaking if you could gap the points at .001" (or less) and trip things off right at the peak of the lobe, you would have the most dwell time possible for the coil to reach saturation. If I understand you correctly, you are saying that the problem comes in with a gap of less than .016" with this setup and you start burning points, is that right? Couldn't the capacitor value be selected to match up with the gap setting? Know anywhere that there might be more info that, I'd like to understand that relationship a little better?
What you say about balancing the loads on the shaft with the dual point system makes complete sense. It’s been 40 years since I’ve seen a distributor machine but I'm sure that problem would show up clear as a bell with a scope on the secondary. What comes to mind is the way the timing marks bounces around when you bring the revs up with a light on it. All of the slop in the system causes the timing to bounce around quite a bit so anything you could do to lessen it is good.
Thanks
Denny Graham
Sandwich, IL

Denny G
Sandwich, IL