CJ2A Operation and Care
Manual -- Proper Maintenance



Due to the presence of carbon monoxide (a poisonous gas in the exhaust of the engine) never run the engine for any length of time while the vehicle is in a small closed garage.  Opening the doors and windows will lessen the danger considerably, but it is safest if adjustments are being made that require the operation of the engine, to run the vehicle out-of-doors.

The old adage "An ounce of prevention is worth a pound of cure" was never more true than when applied to any motor vehicle.  The importance of regular systematic inspection cannot be over-emphasized.  Small and seemingly unimportant faults, if neglected, may grow into expensive major repairs.  Regular inspections and prompt correction of small faults will go far toward holding down maintenance expense, eliminating delays in productive operations and upholding the high standard of reliability and performance built into your "Jeep" at the factory.

For best performance and dependability the engine should have a periodic tune-up twice yearly, preferably in the Spring and Fall.

NOTE: Should the engine fail to perform satisfactorily and the trouble is definitely traced to the carburetor, consult your Willys-Overland Dealer.  Carburetor service is specialized and should not be undertaken unless the unit is thoroughly understood.

Inlet opens 9 degrees before top centre
Inlet closes 50 degrees after bottom centre
Exhaust opens 47 degrees before bottom centre
Exhaust closes 12 degrees after top centre
Spark Setting

Spark set top centre with automatic spark controls at rest, when using low octane fuel.

Firing Order
Tappet setting for valve timing
Number of flywheel teeth

Piston Measurements
From Top Centre
.039"   (9.91 mm.)
3.772" (95.81 mm.)
3.799" (96.49 mm.)
.054"   (0.14 mm.)
"IGN" 5º BTC
.020"   (0.51 mm.)

To check the valve timing, adjust the inlet valve tappet No. 1 cylinder to .020" (0.51 mm.).  Use care in making this adjustment that the measurement is accurate with feeler gauges and that the tappet is resting against the lowest surface of the camshaft cam.  Rotate the crankshaft clockwise until piston in No. 1 cylinder is ready for the intake stroke.  (Mark "I-O" -- intake open -- on the flywheel is in the centre of the engine.)  With the crankshaft in this position, valve timing is correct if No. 1 intake valve tappet is jut tight against the end of the valve stem.  After checking, adjust all of the tappets .014" (0.356 mm.).

Should the timing be incorrect it is advisable to consult your Willys-Overland Dealer.

1. Condenser
2. Lubricating Wick
3. Breaker Arm Pivot
4. Breaker Cam
5. Distributor Points
6. Oiler
7. Adjustment Lock Screw
8. Adjusting Screw
The breaker points should be cleaned and adjusted to .020" (0.51 mm.) opening.  Remove all of the spark plugs except No. 1.  Rotate the crankshaft until No. 1 piston is coming up on the compression stroke which can be determined by the resistance in the cylinder.  Remove the spark plug and continue to turn the engine slowly until the mark "IGN" on the flywheel is in the centre of the timing hole at the right rear.  This places the piston in the correct position to set the ignition.
Loosen the distributor clamp and rotate the distributor assembly until the distributor rotor arm points to No. 1 terminal in the distributor cap and the distributor points just start to break.  To advance the timing, turn the distributor in a clockwise direction; to retard it, turn in a counter-clockwise direction.  Tighten the clamp screw firmly but do not overtighten it.

The engine firing order is 1-3-4-2.

After setting the timing, revolve the crankshaft two complete turns, to make sure all backlash is eliminated, and check the timing to the flywheel mark "IGN".

Ignition timing must be accurately set to obtain the maximum efficiency of the engine.  Information above is given only to enable the operator to place the vehicle back in service should trouble develop.  At the first opportunity, have your Willys-Overland Dealer check the setting with a neon timing lamp which can also be used to check the automatic spark advance operation, by accelerating the engine.

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