Gravely Convertible 10 Shop Manual page 13

Always replace badly burned or pitted breaker points. A certain amount of build up or metal transfer
occurs under normal operating conditions; however, if this occurs too frequently and becomes excessive, the
condenser may be at fault -- see Condenser Service for details. Slightly pitted points can be dressed down
with a point file, although this should be done only as a temporary field fix Replace points at first opportunity
after filing. If the points are oxidized, rub a piece of coarse cloth between the surfaces. Dirty or oily points
can be cleaned with cloth but make sure no particles of lint are left between surfaces.
CONDENSER
If the condenser shorts out, the coil will be unable to release output voltage. On the other hand, if it opens
or decreases in capacitance, the ignition points will burn excessively. If badly burned breaker points occur too
frequently, the condition of the condenser should be suspected. If condenser has too small capacitance, metal
will transfer from the stationary contact to the movable contact. If its capacitance is too large, the metal will
build up on the stationary contact.
The condenser can be tested with an ohmmeter or a commercial condenser tester. To check with the
ohmmeter, remove the condenser then connect leads between the condenser lead and a good ground on the
engine. At first, a low resistance should be indicated; however, this should very quickly rise to a high value. If
low resistance is indicated continuously, the condenser is definitely faulty and must be replaced. When using
a commercial condenser tester, follow instructions given by the tester manufacturer.
IGNITION COIL
Ignition coils do not require servicing on a regular basis, however, the coil should be kept in clean
condition and the terminals and connections must be tight to provide good electrical contact. The rubber
nipple on the high tension terminal must be in good condition to prevent leakage of current across exposed
surfaces. The coil must be hooked up properly.
TESTING: Special test instruments are required to accurately test ignition coils. When using such
equipment, carefully follow instructions stated by the tester manufacturer. A coil can be checked for opens
with a simple test lamp. To test for an open primary winding, connect the two test points to the primary
terminals - the lamp will not light if the circuit is open.
To check the secondary circuit, connect one test point to the high tension terminal and the other point to either
of the primary terminals. In this case, the lamp will not light but tiny sparks should be noted as the test points
are rubbed across the terminals. If the secondary is opened, no sparks will occur. If the tests show that the
primary or secondary is open, replace coil or test further with the coil tester.
Figure 8 Typical Magneto Ignition Coil
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