dwell meter measures the dwell angle of the contact points in the
A dwell meter is much more accurate than setting the points gap
with a feeler gauge.
The dwell angle of the points is the angle of point closure; the
smaller the dwell angle, the smaller the dwell angle, the wider
the points gap, and vice-versa. Workshop manuals will give the specification
for the dwell angle in the tuning data section.
A dwell meter is particularly useful in the case of used points
where metal transfer between the points makes accurate checking
difficult using feeler gauges. To
carrying out the dwell angle measurement, the dwell meter is connected
in accordance with the manufacturer's instructions. The engine is
started and run at idle, and the dwell angle read off the meter.
If the reading is outside the prescribed limits, the distributor
cap and rotor arm must be removed and the contact breaker points
adjusted to the correct setting, while the engine is cranked over
on the starter. When the dwell angle has been adjusted, the ignition
timing must be reset.