Long Block Replacement

Complete removal and replacement of the 390ci V8 long block assembly, including all internal engine components from oil pan to cylinder heads.

Warnings

Tools required

Parts

• 390ci V8 long block assembly × 1 — Use OEM specification or remanufactured equivalent
• Intake manifold gasket set × 1 — Use OEM specification
• Exhaust manifold gaskets × 1 — Use OEM specification
• Oil pan gasket × 1 — Use OEM specification
• Timing cover gasket × 1 — Use OEM specification
• Engine oil filter × 1 — Use OEM specification
• Engine coolant × 1 — Use ethylene glycol antifreeze
• Engine oil × 1 — 10W-30 or 10W-40
• Water pump gasket × 1 — Use OEM specification
• Thermostat housing gasket × 1 — Use OEM specification
• Fuel pump gasket × 1 — Use OEM specification
• Motor mount hardware × 1 — Grade 8 bolts recommended

Fluids

• Engine oil (10W-30 or 10W-40) — 5 qt
• Engine coolant (ethylene glycol antifreeze) — 16 qt

Preparation

1. Position vehicle on level surface and engage parking brake
2. Disconnect negative battery cable, then positive battery cable
3. Remove hood for clearance by marking hinge positions and unbolting with assistant
4. Drain engine oil completely into appropriate container
5. Drain cooling system by opening radiator petcock and removing lower radiator hose
6. Relieve fuel system pressure by loosening fuel line at carburetor
7. Place protective fenders covers to prevent damage during engine removal
8. Take detailed photographs of engine bay for reference during reassembly

Procedure

1. 1

   Remove air cleaner and fuel system components
   Remove air cleaner assembly and disconnect fuel line from carburetor. Cap or plug fuel line to prevent spillage. Disconnect throttle linkage, kickdown linkage (if automatic transmission), and cruise control cable if equipped. Label all vacuum lines connected to carburetor and intake manifold, then disconnect and route clear of engine.
2. 2

   Disconnect cooling system components
   Remove upper and lower radiator hoses from engine. Disconnect heater hoses at firewall and engine. Remove radiator shroud if equipped, then remove radiator by unbolting mounting brackets. Disconnect automatic transmission cooler lines if equipped. Remove fan, fan clutch or flex fan assembly, and water pump drive belts. On Machine models, mark and remove the Ram Air ducting.
3. 3

   Disconnect electrical system
   Disconnect alternator wiring harness and remove alternator. Disconnect starter motor cables and wiring. Label and disconnect all engine sensors including oil pressure sender, temperature sender, and coil primary wire. Disconnect distributor primary wire. Remove spark plug wires from distributor cap and route clear of work area.
4. 4

   Remove exhaust system connections
   Working from underneath vehicle on jack stands, disconnect exhaust pipes from exhaust manifolds. The Rebel Machine uses dual exhaust - disconnect both sides at the manifold flanges. Remove exhaust manifold bolts and remove manifolds from cylinder heads if they will not be reused with new long block. Otherwise, manifolds may remain attached during removal.
5. 5

   Disconnect transmission from engine
   Remove bellhousing-to-engine block bolts accessible from above. Support transmission with transmission jack or floor jack with wood block. Remove remaining bellhousing bolts from underneath. On automatic transmissions, mark flexplate-to-torque converter relationship and remove converter bolts through access hole. On manual transmissions, disconnect clutch linkage. Separate transmission from engine block slightly to clear input shaft from clutch or flexplate.
6. 6

   Remove accessories and external components
   Remove power steering pump (if equipped) and secure to frame with wire without disconnecting hoses. Remove air conditioning compressor (if equipped) and secure to frame without disconnecting refrigerant lines. Remove motor mount through-bolts on both engine mounts. Remove any remaining brackets, ground straps, or accessories still attached to engine block.
7. 7

   Attach engine hoist and verify clearance
   Install engine leveler on hoist chain and attach to engine using intake manifold bolts or dedicated lift bracket points. The 390 AMC has lifting eyes cast into block - use these if accessible. Take up slack in hoist chain and verify engine balance. Check that all connections have been disconnected and no hoses, wires, or linkages remain attached.
8. 8

   Lift and remove engine assembly
   Slowly raise engine while guiding clear of transmission input shaft or flexplate. Angle engine as needed using leveler to clear firewall, shock towers, and front crossmember. The 390 is tall due to its deck height - raise front of engine first to clear bellhousing, then level out as it clears the engine bay. Continue lifting until engine clears vehicle completely, then move hoist forward away from vehicle.
9. 9

   Transfer external components to new long block
   Mount old engine on engine stand. Transfer the following components to new long block: intake manifold, carburetor, distributor, fuel pump, water pump, thermostat housing, oil pan (if not included), timing cover (if not included), harmonic balancer, motor mounts, exhaust manifolds, oil pressure and temperature sending units, and all brackets. Install new gaskets for all components being transferred. Verify new long block includes all internal components: crankshaft, pistons, connecting rods, camshaft, lifters, cylinder heads, and valve train.
10. 10

    Prepare new long block for installation
    Verify all freeze plugs are properly installed and not leaking. Check that all threaded holes are clean and undamaged. Pre-lubricate engine by removing distributor and using priming tool to spin oil pump until oil pressure builds. Rotate engine by hand to verify smooth rotation. Install new oil filter. Attach engine hoist and leveler to new engine using same lifting points.
11. 11

    Install new long block into vehicle
    Position engine hoist over engine bay. Lower engine slowly while guiding into position. Angle engine to clear firewall and front crossmember - typically front tilted up first, then lowering rear as engine enters bay. Align engine with transmission bellhousing, ensuring torque converter or clutch disc aligns properly. Guide engine onto motor mounts while continuing to align with transmission.
12. 12

    Secure engine and transmission connection
    Install motor mount through-bolts finger-tight on both sides. Align bellhousing to engine block and install all bellhousing bolts, working in star pattern from center outward. On automatic transmissions, rotate flexplate to access and install torque converter bolts per previously marked positions. Tighten motor mount bolts fully. Remove engine hoist after verifying engine is fully supported.
13. 13

    Reconnect cooling and fuel systems
    Install radiator and secure mounting brackets. Reconnect automatic transmission cooler lines if equipped. Install water pump drive belts and adjust to proper tension. Connect upper and lower radiator hoses using new clamps. Connect heater hoses. Reconnect fuel line to carburetor using new line if original shows deterioration. Install Ram Air ducting on Machine models.
14. 14

    Reconnect exhaust and electrical systems
    Install exhaust manifolds if removed, using new gaskets. Connect exhaust pipes to manifolds with new gaskets and hardware. Install alternator and connect wiring. Connect starter motor cables and wiring. Reconnect all sensors, distributor wiring, and coil primary wire per labels applied during disassembly. Reinstall spark plug wires to correct cylinders following firing order 1-8-4-3-6-5-7-2.
15. 15

    Reconnect accessories and linkages
    Reinstall power steering pump and air conditioning compressor if equipped. Reconnect all vacuum lines per labels. Connect throttle linkage, kickdown linkage, and cruise control cable if equipped. Verify all linkages operate freely through full range of motion. Install fan assembly and air cleaner. Reinstall hood using marked positions.

Reassembly

1. Fill cooling system with 50/50 mixture of antifreeze and distilled water to proper level
2. Fill crankcase with 5 quarts of proper weight engine oil (10W-30 or 10W-40)
3. Double-check all fluid levels including engine oil, coolant, power steering, and transmission
4. Verify all electrical connections are secure and properly routed
5. Confirm all vacuum lines are connected per labels and not kinked or damaged
6. Reconnect battery cables (positive first, then negative)

Verification

• Before starting, verify no tools or rags remain in engine bay
• Check for any fluid leaks around oil pan, timing cover, intake manifold, and coolant connections
• Prime fuel system by cranking engine briefly without starting
• Start engine and verify immediate oil pressure indication on gauge
• Allow engine to warm to operating temperature while monitoring for leaks, unusual noises, or overheating
• Check cooling system for leaks and verify thermostat opens by monitoring temperature gauge and feeling upper radiator hose
• Verify proper operation of all gauges, accessories, and charging system
• Check and adjust idle speed and ignition timing to factory specifications
• Road test vehicle to verify proper operation under load, checking for overheating, oil pressure, and abnormal noises
• Recheck all fluid levels after test drive and inspect for any new leaks
• Perform initial oil and filter change after 500 miles of break-in operation

More procedures for this vehicle