Cylinder Head Resurface

This procedure covers removal, machining, and reinstallation of the cylinder heads on the 1970 AMC Rebel Machine's 390ci V8 engine to restore proper sealing surfaces and compression.

Warnings

Tools required

Parts

• Cylinder head gaskets (set of 2) × 1 — Use OEM specification for AMC 390
• Intake manifold gasket set × 1 — Use OEM specification
• Exhaust manifold gaskets × 2 — Use OEM specification
• Valve cover gaskets × 2 — Use OEM specification
• Cylinder head bolt set × 1 — Replace if threads show wear
• Pushrods (if worn or bent) × 16 — Inspect before reuse
• Rocker arm pivot balls (if worn) × 16 — Inspect before reuse
• Coolant × 1 — Ethylene glycol antifreeze

Fluids

• Engine coolant — 14 qt
• Engine oil — 5 qt

Preparation

1. Disconnect negative battery cable
2. Drain engine coolant into appropriate container
3. Label and disconnect all vacuum lines, electrical connections, and linkages from carburetor and intake manifold
4. Remove air cleaner assembly
5. Tag spark plug wires for cylinder identification and remove wires
6. Position drain pan to catch any residual coolant or oil

Procedure

1. 1

   Remove valve covers and accessories
   Remove both valve covers by unbolting the retaining bolts. Remove alternator, power steering pump (if equipped), and air injection pump with brackets as necessary to access cylinder heads. Keep hardware organized by component.
2. 2

   Remove intake manifold
   Disconnect fuel line from carburetor. Remove carburetor if necessary for clearance. Unbolt and remove intake manifold bolts in reverse order from center outward. Carefully lift intake manifold from engine, breaking gasket seal with gentle prying if needed. Cover open ports with clean rags to prevent debris entry.
3. 3

   Remove exhaust manifolds
   Disconnect exhaust pipes from both exhaust manifolds at the flange connections. Remove exhaust manifold bolts and remove both manifolds. Inspect manifolds for cracks while removed.
4. 4

   Remove rocker arm assemblies
   Loosen each rocker arm nut while keeping pushrods in place. Remove rocker arm nuts, pivot balls, and rocker arms. Keep each rocker assembly organized by cylinder number. Remove all 16 pushrods and store them in order to ensure reinstallation in original positions. Inspect pushrods for wear or bending.
5. 5

   Remove cylinder head bolts
   Remove cylinder head bolts in reverse numerical sequence, working from outer bolts toward center in a crossing pattern. This prevents head warping during removal. On AMC 390, work progressively from ends toward center. Keep bolts in order and inspect threads for damage or stretching.
6. 6

   Remove cylinder heads
   Carefully lift cylinder heads straight up from engine block. Heads may be stuck due to gasket seal; gently tap with rubber mallet or carefully pry at designated pry points only (never between sealing surfaces). Remove and discard old head gaskets. Place heads on clean work surface with combustion chambers facing up.
7. 7

   Inspect cylinder heads for damage
   Clean all gasket material from head mating surfaces using gasket scraper, taking care not to gouge aluminum or cast iron. Clean combustion chambers and valve seats. Use straightedge and feeler gauge to check head flatness across multiple planes (lengthwise, widthwise, and diagonally). If warpage exceeds 0.003" over any 6" span or 0.006" total length, resurfacing is required.
8. 8

   Transport heads to machine shop
   If valves are remaining installed, protect valve faces during transport. Provide machine shop with specifications: AMC 390 V8, maximum material removal 0.010", target surface finish 60-80 RMS. Request pressure testing if overheating or gasket failure was the cause of resurfacing need. Request valve guide and seat inspection.
9. 9

   Clean engine block surfaces
   While heads are at machine shop, thoroughly clean block deck surfaces of all old gasket material. Use gasket scraper carefully to avoid gouging surfaces. Clean out head bolt holes using thread chaser or tap to remove any debris or old thread sealer. Blow out holes with compressed air. Cover cylinders with clean rags to prevent debris entry.
10. 10

    Install resurfaced cylinder heads
    Once heads return from machine shop, verify cleanliness of both head and block surfaces. Position new head gaskets on block, ensuring correct orientation (typically marked 'FRONT' or 'TOP'). Carefully lower heads onto block, aligning with dowel pins. Install head bolts with light oil or thread sealer as specified by gasket manufacturer. Torque head bolts in three progressive stages (typically 30 ft-lbs, 60 ft-lbs, then final spec around 100-110 ft-lbs for AMC 390) following proper tightening sequence from center outward in a crossing pattern. Note: Without specific torque specs in database, consult factory service manual for exact values.
11. 11

    Install pushrods and rocker assemblies
    Install each pushrod in its original position, ensuring proper seating in lifter. Install rocker arms with pivot balls and nuts. Adjust valve lash: rotate engine to position lifter on base circle of cam lobe, then tighten rocker nut until zero lash is achieved, then tighten additional 1/2 to 1 full turn (hydraulic lifter preload). Repeat for all 16 valves.
12. 12

    Reinstall exhaust and intake manifolds
    Install new exhaust manifold gaskets and bolt exhaust manifolds to heads. Connect exhaust pipes to manifolds. Install new intake manifold gaskets (use correct end seals). Position intake manifold and install bolts, torquing from center outward in crossing pattern. Typical AMC intake manifold torque is 35-45 ft-lbs, but verify with service manual.
13. 13

    Reinstall accessories and valve covers
    Install new valve cover gaskets. Install valve covers with even torque (typically 4-6 ft-lbs for valve covers). Reinstall alternator, power steering pump, and air injection equipment. Reconnect all vacuum lines, electrical connections, and linkages according to original tags.
14. 14

    Refill fluids and initial startup
    Refill cooling system with proper coolant mixture. Check engine oil level and top off as needed. Reconnect battery. Before starting, prime oil system by cranking engine without spark to build oil pressure. Install spark plugs and wires according to firing order tags. Start engine and check immediately for oil pressure, coolant leaks, and unusual noises.

Reassembly

1. Double-check all torque specifications against factory service manual values
2. Verify all vacuum lines and electrical connections are properly reconnected
3. After initial startup and warm-up, recheck cylinder head bolt torque after engine cools (recommended after first heat cycle)
4. Retorque intake manifold bolts after first heat cycle if recommended by gasket manufacturer

Verification

• Engine should idle smoothly without excessive noise or valve train clatter
• Check for coolant leaks at head gaskets and intake manifold gaskets
• Check for oil leaks at valve covers
• Verify proper oil pressure on gauge (30-60 PSI at operating temperature)
• Monitor engine temperature to ensure proper cooling system function
• Road test vehicle and recheck for leaks after reaching full operating temperature
• Perform compression test to verify cylinder sealing if resurfacing was done to correct compression issues

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