0312944 JOHNSON SCREW,Cam

CHECKING CONTACT POINT OPENING
1-Contact point bumper block on one of the highest elevations of the cam.
ADJUSTING CONTACT POINT OPENING
2-Bracket fastening screws. 3-Slot. Adjusting Contact Point Opening: Loosen the screws (2) which hold the adjustable contact point bracket and move the bracket by inserting a screwdriver in the slot (3) and turn either clockwise or counterclockwise until the correct point opening is obtained. Then tighten the fastening screws and recheck the adjustment.
REMOVING CONTACT POINTS
4-Spring clamp screw. 5-Lock and washer. To Remove the Contact Points: To remove the contact points, remove the spring clamp screw (4) and the two screws (2) used in adjusting the contact point opening.On earlier magnetos, also remove the lock and washer (5) which retain the movable contact point. Testing: A magneto can be tested when coupled to the engine. Remove the cable from a spark plug (rotate the terminal to facilitate removal), insert a 1/4 inch (6 mm.) bolt or similar metal object into the terminal to contact the wire, and hold the terminal so the end of the bolt is 1/8 inch (3.17 mm.) away from the metal base of the spark plug. Turn the magneto switch ON and crank the engine. If no spark occurs between the bolt and the spark plug base, disconnect the switch wire from the terminal on the magneto and test again. If a spark now occurs with the switch wire removed, the wire from the magneto to the switch has become grounded or the switch requires replacement. If, with the switch wire off, the magneto still does not fire, remove the magneto as instructed in the next paragraph and take it to your Caterpillar dealer for testing. To Remove the Magneto for Testing: Disconnect the cables from the magneto. One of the cables should be tagged or marked in some convenient manner which will designate the proper position of these cables. Remove the two bolts that hold the magneto to the timing gear cover and lift off the magneto. To Time the Magneto to the Engine: To time the magneto to the engine, proceed as follows:1. Locate the "X" mark (1) on the starting engine magneto drive.2. Turn the magneto impulse coupling until the "X" mark (2) on the tang is in such a position as to line up with the mark on the magneto drive.
TIMING MARKS
1-Mark "X" on magneto drive. 2-Mark "X" on the impulse coupling tang.3. Install the magneto with the "X" marks together and tighten the bolts. To Reconnect Magneto Wires: To reconnect the magneto wires proceed as follows:1. Place the spark plug wire from number 1 cylinder (the cylinder farthest away from the flywheel) into the number 1 wire receptacle of the magneto cap.2. Reconnect the other spark plug wire.3. Reconnect ground wire.American-Bosch Magneto
Do Not Lubricate the Magneto at Any Point: The bearings are packed with a ball and roller bearing grease when assembled, and this should be replaced only when the magneto is taken to your Caterpillar dealer for checking or reconditioning. Checking Contact Point Opening. Every 1000 service hours check the contact point opening.To check, first remove the distributor plate which is held in place by four screws. Care should be taken in removing the plate not to damage the gasket. Clean any carbon dust from inside the plate by using a soft cloth dampened with a nonflammable cleaning fluid. Remove the distributor rotor, then turn the engine until the contact point bumper block (1) is on one of the highest elevations of the cam. Check the clearance with a thickness gauge between the contact points as illustrated. This clearance should be .014 to .018 inch (.36 to .46 mm.).
CHECKING CONTACT POINT OPENING
1-Contact point bumper block on one of the highest elevations of the cam.
ADJUSTING CONTACT POINT OPENING
2-Bracket fastening screws. 3-Eccentric slotted screw. Adjusting Contact Point Opening: Loosen the screws (2) which hold the adjustable contact point bracket and move the bracket by inserting a screwdriver in the eccentric slotted head screw (3) and turn either clockwise or counterclockwise until the correct point opening is obtained. Then tighten the fastening screws and recheck the adjustment. Testing: A magneto may be tested when coupled to the engine by turning the switch, ON, removing the cable from a spark plug, and holding the terminal 1/8 inch (3.17 mm.) away from the metal base of the plug while cranking the engine. If no spark passes from the terminal to the metal base, disconnect the magneto switch wire from the magneto where it is connected to the terminal on the top of the magneto housing and test again. If a spark passes from the terminal to the base with the switch wire removed, the wire running from the magneto to the switch has become grounded or the switch requires replacement. If, with the switch wire off, the magneto still does not fire, remove the magneto as instructed in the next paragraph and take it to your Caterpillar dealer for testing. To Remove the Magneto for Testing: Disconnect the cables from the magneto. One of the cables should be tagged or marked in some convenient manner which will designate the proper position of these cables. Remove the two bolts that hold the magneto to the timing gear cover and lift off the magneto. Do not remove the magneto mounting trunnion when lifting the magneto from the engine. To Time the Magneto to the Engine: Check the adjustment of the contact points. Locate the firing point of No. 1 cylinder by removing the cover from the top of the starting engine clutch housing and the spark plug from No. 1 cylinder. Crank the engine slowly until air is forced from the spark plug opening. This indicates the piston is coming up on the compression stroke. Place a 3/8 inch x 2 inch bolt (1) in the hole in the flywheel housing. Continue to turn the crankshaft slowly until the bolt drops in the hole in the flywheel. Remove the bolt and replace the cover.
LOCATING CORRECT POSITION