First list message for a couple of days.
Points or some kind of electronic ignition? Could be points bounce, or some
other wear or maladjustment in the distributor, possibly a condenser on the
way out, or an intermittent ground wire in the distributor, or coil wire
where it passes through the distributor body. These last two are
continually flexed back and fore as the points plate moves with changing
vacuum. However all of these are likely to cause misfiring as well, but if
the tach is going *up* rather than down implies *extra* pulses which are
less likely to cause misfiring. A multi-meter with a tach range could tell
you if it is the pulses that are faulty (by also showing higher revs than
should be) or the tach (by indicating the correct) revs. However if it has
better filtering it could indicate steady revs when the tachometer goes
high, even if it is the pulses that are the problem.
PaulH.
----- Original Message -----
> At the high RPM band my Tach started jumping a couple of thousand
> revolutions, at the low band the Tach is pretty steady, is this an
electrical
> problem or is the Tach on it's last leg.
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