Dear Dave and everyone,
Some ideas that spring to mind are:
1) Check the distributor clamp bolt is tight and really is holding. I
once wasted hours carefully making tiny vernier adjustments of fractions
of a degree, and then found the distibutor could twist around by itself
+/- 10 degrees
2) Are you following all the rules about timing procedures ? eg correct
idling speed, vacuum pipe disconected and plugged, no wear in the
distributor bushes or cams, etc ? Anything that can give an erratic
setting can give a different result on different occasions, so you never
know where your starting point is.
3) Make sure the advance and retard mechanism is working and not worn,
or the springs stretched or broken. If turned manually, the upper shaft
should snap back when released. A sluggish movement will not always
return to the same place so will give a different timing position.
4) Check that the rotating base plate is not worn. If the points
mounting can wobble about then again it gives an erratic setting.
Hope these ideas may help.
Best wishes,
Cliff Pope
PS Thanks for the ideas re centralising jets. Of course winding the jet
up first to centralise, then lowering again, is obvious when you think
about it.
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