TM 5-4240-501-14PIGNITIONMagna-MaticArmature Air GapArmature air gap on engines equipped with Magna-Maticignition is fixed and can change only if wear occurs oncrankshaft journal and/or main bearing. Check for wearby inserting a feeler gauge 1/2" (12.7 mm) in width atpoints between the rotor and armature. Minimum feelergauge thickness is .004" (0.1 mm). (Keep feeler gaugeaway from magnets on rotor or you will have a falsereading.) Fig. 47.Fig. 47 - Checking Armature GapMagna-Matic IgnitionRemove RotorThe rotor is held in place by means of a Woodruff keyand a clamp on later engines, and a Woodruff key andset screw on older engines. Fig. 48. THE ROTORCLAMP MUST ALWAYS REMAIN ON THE ROTOR(UNLESS THE ROTOR IS IN PLACE ON THECRANKSHAFT AND WITHIN THE ARMATURE) OR ALOSS OF MAGNETISM WILL OCCUR.Loosen the socket head screw in the rotor ecoup,allowing the clamp to loosen. It may be necessary to usea puller to remove the rotor from the crankshaft. Onolder models, loosen the small lock screw, then the setscrew.Fig. 48 - RotorInstall RotorIf rotor has a set screw, Fig. 48, Illus. 2, place theWoodruff key in keyway on crankshaft, then slide rotoronto crankshaft until the set screw hole in rotor andcrankshaft are aligned. Be sure the key remains inplace. Tighten the set screw securely, then tighten thelock screw to prevent set screw from loosening. Thelock screw is self-threading and the hole does not requiretapping.If rotor has a clamp, Fig. 48, Illus. 1, place the Woodruffkey in place in crankshaft, align keyways in rotor withWoodruff key. If necessary, use a short length of pipeand hammer to drive rotor onto shaft until .025"(0.64mm) feeler gauge can be inserted between rotorand bearing support. Split in clamp must be betweenslots in rotor. Tighten clamp lock screws 60 to 70 inchpounds (.7 - .8 kg m or 6.8 - 8.0 newton m). Fig. 49.Fig. 49 - Install RotorAdjust Rotor TimingThe rotor and armature are correctly timed at the factoryand require timing only if the armature has beenremoved from the engine, or if the cam gear orcrankshaft has been replaced.If necessary to adjust, proceed as follows: With the pointgap set at .020" (0.5 mm) turn the crankshaft in normaldirection of rotation until breaker points close and juststart to open. Use a timing light or insert a piece oftissue paper between the breaker points to determinewhen points begin to open. With the three armaturemounting screws slightly loose, rotate the armature untilthe arrow on armature lines up with the arrow on rotor asshown in Fig. 50. Align with corresponding number ofengine model. On Models 9, align with 9, etc. Retightenarmature mounting screws.213
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business
