The timing mechanism in the
system causes the sparkplug to fire in each
just before the
reaches top dead centre (
) on its
That gives time for the mixture to start burning steadily as the piston passes through TDC. The resulting expansion of burning gases will thereby be most effectively used throughout the
The timing of the
is measured as the number of degrees by which the
is short of bringing the piston in the timing cylinder (usually No. 1, but consult the handbook for your car) to TDC.
The number of degrees varies from car to car (again consult the handbook).
means setting the timing with the
You set the crankshaft at the correct number of degrees before top dead centre, then adjust the
by turning it until the contact-breaker points are just opening.
However, this method of timing takes no account of wear and
between two parts such as the teeth of gears. data-term-id="1310">backlash
in the distributor drive. The timing can be slightly out, even at idling speed. The spark will occur later than it should, particularly at high
speed, and the engine will not develop full power.
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