04-04-2022, 10:10 AM
Hi
Just to quantify the effect of changing the points gap, here is a graph I once drew after some bench measurements on an unworn distributor. The standard gap of 12 thou gives about a 50 degree dwell angle (the time the points are closed and current is building up in the coil). As you set a greater gap, the dwell reduces which will slightly reduce ignition energy at high RPM. The timing also shifts, so best to reset timing after re-gapping.
Once the spindle bearings wear, this is all thrown out of the window and the timing and dwell will be all over the place as the cam wobbles depending on revs. Opening up the points is probably the best short term move, as it reduces the sensitivity to wear at the expense of a slightly reduced dwell and energy at high RPM, something you can probably live with. In the long term, a new or reconditioned distributor is called for.
Points Gap Effect.jpg (Size: 46.37 KB / Downloads: 117)
Just to quantify the effect of changing the points gap, here is a graph I once drew after some bench measurements on an unworn distributor. The standard gap of 12 thou gives about a 50 degree dwell angle (the time the points are closed and current is building up in the coil). As you set a greater gap, the dwell reduces which will slightly reduce ignition energy at high RPM. The timing also shifts, so best to reset timing after re-gapping.
Once the spindle bearings wear, this is all thrown out of the window and the timing and dwell will be all over the place as the cam wobbles depending on revs. Opening up the points is probably the best short term move, as it reduces the sensitivity to wear at the expense of a slightly reduced dwell and energy at high RPM, something you can probably live with. In the long term, a new or reconditioned distributor is called for.
Points Gap Effect.jpg (Size: 46.37 KB / Downloads: 117)