Willys CJ-2A - Engine Performance Issues; Misfires, Power Loss, and Overheating

• Improper valve timing.
• Clutch slipping.
• Exhaust pipe or muffler obstructed.
LACK OF COMPRESSION
• Faulty cylinder head gasket.
• Insufficient tappet clearance.
• One or more improperly fitted pistons or piston rings.
• Valves not seating properly.
POPPING BACK THROUGH THE CARBURETOR
(This usually indicates a too lean mixture.)
• Dirt in carburetor. (Fuel pump strainer dirty, see FUEL SYSTEM.)
• Water in fuel.
• Air leak at intake manifold connections.
• Incorrect ignition timing.
• Incorrect valve timing.
• Inlet valves holding open.
• Spark plug wires connected to incorrect plugs. Firing order 1-3-4-2.
ENGINE OVERHEATING
• Lack of proper lubrication.
• Stoppage of water circulation, faulty thermostat ot lack of water.
• Slipping fan belt.
• Ignition timing improperly set.