What is the importance of Dwell? October 20, 2016.
Setting points using a dwell meter is more accurate than setting them with a feeler gauge. The Ferguson Factory shop manual, and On The Farm Manual indicate this. Used ignition points, even when “dressed” to remove the buildup that occurs on one contact does not address the pitting that occurs on the other contact. Once the original flat factory surface on the contacts is gone, it is impossible to get an accurate measurement with a feeler gauge. That’s the reason you will often see two point gap settings listed in the specifications, one for new points, and one for used points. In reality both of these measurements are an approximation of the dwell setting which can only be determined electronically. Even setting the points with a dial gauge will not result in the correct dwell setting, it has to be measured electronically.
Most “mechanics” are working in point gap, setting them to the specified 0.022″. This gap may be the wrong setting if you have wear, the wrong point, or low quality parts. Setting a point on a properly maintained engine will get you the proper dwell. But, working with older, worn, and sometimes poorly maintained engines, setting a point may not be sufficient.