Rocker Arms - All

Complete replacement of all rocker arms on the AMC 390ci V8 engine, including removal of valve covers, pushrods, and rocker arm assemblies.

Warnings

Tools required

Parts

• Rocker arm assembly (left bank) × 1 — Use OEM specification
• Rocker arm assembly (right bank) × 1 — Use OEM specification
• Valve cover gasket (left) × 1 — Use OEM specification
• Valve cover gasket (right) × 1 — Use OEM specification
• Valve cover grommets × 1 — Use OEM specification
• Rocker arm shaft retaining bolts × 1 — Use OEM specification or reuse if undamaged

Fluids

• Engine oil (SAE 10W-30 or 10W-40) — 1 qt

Preparation

1. Disconnect negative battery cable
2. Remove air cleaner assembly and disconnect PCV valve hose
3. Label and disconnect spark plug wires from both valve covers, routing them away from work area
4. Disconnect any vacuum lines, breather hoses, or accessories mounted to valve covers
5. Remove distributor cap and lay aside without disconnecting wires
6. Place drain pan under engine to catch any oil drips

Procedure

1. 1

   Remove valve covers
   Remove the valve cover retaining bolts from both valve covers (typically 4-6 bolts per cover). Carefully lift off valve covers. If covers are stuck, gently tap with rubber mallet; do not pry between cover and head to avoid damaging sealing surfaces.
2. 2

   Inspect and photograph valve train layout
   Before disassembly, visually inspect the rocker arm assemblies and note the orientation of components. Take photos if available to document the correct positioning of rocker arm shaft assemblies, bridge pieces, and rocker arms. Note that AMC 390 uses a shaft-mounted system with specific orientation.
3. 3

   Remove rocker arm shaft assemblies
   Remove the rocker arm shaft retaining bolts in a progressive pattern, loosening each bolt 1-2 turns at a time working from the ends toward the center. This prevents bending the shaft. Once all bolts are removed, lift the entire rocker arm shaft assembly off the cylinder head as a unit. Repeat for the opposite bank.
4. 4

   Remove and organize pushrods
   Carefully lift out all pushrods from their lifter seats, keeping them in order. Place pushrods in a numbered rack or container to maintain their original positions (intake vs exhaust, cylinder 1-8). Inspect pushrod ends for wear, scoring, or mushrooming. Pushrods should be reused in their original locations.
5. 5

   Disassemble rocker arm shaft (if needed)
   If replacing individual rocker arms or inspecting components, note the position of rocker arms, bridges, and spacers on the shaft. Remove retaining pins or clips at shaft ends and slide components off. Keep all parts organized. AMC 390 rocker shafts have oil holes that must face downward during reassembly.
6. 6

   Clean cylinder head mating surfaces
   Thoroughly clean the valve cover gasket surfaces on both cylinder heads using a gasket scraper. Remove all old gasket material and oil residue. Clean rocker arm shaft mounting pads. Wipe surfaces clean with shop rags and brake cleaner. Inspect for damage or warping.
7. 7

   Prepare new rocker arm assemblies
   If installing new rocker arm shaft assemblies, verify correct orientation: oil holes in shaft face downward toward valve stems. Ensure rocker arms are positioned correctly over intake and exhaust valves. Pre-lubricate all rocker arm contact points, shaft journals, and pushrod cups with fresh engine oil or assembly lube.
8. 8

   Install pushrods
   Install each pushrod into its original position, ensuring the lower end seats properly in the lifter cup. Coat pushrod ends with engine oil. Pushrods should rotate freely in their lifter seats. Verify correct length pushrods are used (intake and exhaust may differ).
9. 9

   Install rocker arm shaft assemblies
   Position rocker arm shaft assembly onto cylinder head, ensuring oil holes in shaft face downward and each rocker arm aligns with its corresponding pushrod and valve stem. Guide pushrods into rocker arm cups. Start all shaft retaining bolts by hand. Tighten bolts progressively in a crisscross pattern from center outward, bringing assembly down evenly to avoid binding. Final torque per manufacturer specification (consult service manual for exact value, typically 19-25 ft-lbs).
10. 10

    Verify rocker arm geometry and preload
    Rotate engine by hand using crankshaft bolt (clockwise only when viewed from front) and verify all rocker arms operate smoothly without binding. Check that each rocker arm contacts the valve stem center and pushrod cup properly. If hydraulic lifters are used, verify proper lifter preload by checking pushrod-to-rocker clearance per AMC specifications.
11. 11

    Install new valve cover gaskets
    Position new valve cover gaskets on cylinder heads. Replace valve cover bolt grommets with new ones. Some gaskets may require a thin bead of RTV sealant at the front and rear corners where intake manifold meets cylinder head; consult gasket manufacturer instructions.
12. 12

    Install valve covers
    Carefully position valve covers onto cylinder heads, ensuring gaskets remain properly seated. Install retaining bolts with new grommets and tighten in a crisscross pattern to manufacturer specification (typically 35-50 in-lbs for AMC valve covers; do not overtighten as this may distort covers and cause leaks).

Reassembly

1. Reconnect all vacuum lines, breather hoses, and PCV valve
2. Reinstall distributor cap and ensure it is fully seated
3. Reconnect spark plug wires in correct firing order (1-8-4-3-6-5-7-2 for AMC 390)
4. Reinstall air cleaner assembly
5. Reconnect negative battery cable
6. Add approximately 1 quart of fresh engine oil to compensate for oil lost during procedure

Verification

• Start engine and listen for unusual valve train noise such as ticking or clicking; some initial noise is normal until lifters pump up
• Check for oil leaks around valve cover gaskets after engine reaches operating temperature
• Verify smooth engine operation at idle and during light acceleration
• Recheck valve cover bolt torque after first heat cycle (engine cool-down)
• Monitor oil pressure gauge to ensure normal operating pressure
• After 500 miles, inspect valve covers for any signs of oil seepage and retorque if necessary

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