Rick H. wrote: ... have you ever checked the actual gap on a set of points after you set them with a dwell meter just to see what the gap is in thousandths of an inch?
We have, and it's within or very, very close to spec. This is with OEM Kawasaki points on stock street motors. We've seen enough weird points behavior with aftermarket point sets that we just don't attempt to use them anymore.
Plus the gap is different from one set of points to another. The left side has a smaller physical gap. ...
Dunno about that one. Could be inaccurate manufacturing of aftermarket points? As a thought experiment, could the reason be if the points mount(s) are somehow offset closer/farther from the crank axis if it's an aftermarket points plate? Perhaps using a caliper or micrometer to measure from crank axis to the pivot of both points would be informative, and/or from crank axis to each stationary contact. Thinking through it a little more, it might be easier to measure from the same location of the point cam, either on the base circle or at the top of the lobe. Either way, both should be the same,
Rick H.
Dwell is the number of degrees of crank rotation the points are closed, feeding current to the coil primary windings. This current builds a magnetic field within the coil assembly itself.
When the points open, current flow to the primary windings is interrupted, causing the magnetic field to collapse through the secondary windings, which have many more turns of much finer wire than the primaries. The secondary winding is attached to the spark plug. The collapse of the field causes a very rapid rise of high voltage potential in the secondary winding, which results in the spark at the plug gap. Then the points close again, starting the process over. All this happens in a very tiny of a fraction of a second.
The current flow in the primary winding builds the magnetic field until magnetic field saturation is reached, after which continued current fl;ow from the points has no effect on field strength, and only serves to heat the primary needlessly. Once saturation is achieved, we really only care about when primary current flow stops, creating the spark.
Let's say as an example with mechanical points, dwell in
crank degrees is 25 deg. In
clock time at idle, 25 crank deg. is far longer that what's necessary to achieve primary saturation. Now lets look at dwell at 8,000 RPM.
Crank degrees is still 25, but
clock time is only a tiny fraction of what it was at idle. Is this long enough in time to achieve primary saturation? It would require a scope to answer that question. Hopefully the design engineers did their homework.
Dwell time as elapsed clock time usually isn't as critical on stock street motors as it is on highly-tuned, high compression motors that achieve much higher RPM. Electronic ignition modules can be programmed to extend current flow time to the primaries as crank speed increases, while still breaking current flow to the primary at the right time to make a spark.
On a points system, if point gap is too small, excessive arcing can occur resulting in rapid pitting of the contacts regardless if dwell in crank degrees is correct or not.
If we haven't lost you yet, all this is to say that if the gap isn't too small when dwell in crank degrees is correct, the gap being larger than spec on the other set is unlikely to be a problem, as long as dwell in degrees is also correct.
Good Ridin'
slmjim & Z1BEBE