Replacement of the front engine mounts on a 1970 AMC Rebel Machine with 390ci V8 engine to restore proper engine positioning and eliminate excessive vibration or movement.

Warnings

Tools required

Parts

• Front engine mount (driver side) × 1 — Use OEM specification or equivalent
• Front engine mount (passenger side) × 1 — Use OEM specification or equivalent

Preparation

1. Park vehicle on level, solid ground and engage parking brake
2. Allow engine to cool completely if recently operated
3. Disconnect negative battery cable to prevent electrical shorts
4. Apply penetrating oil to all visible engine mount fasteners and allow to soak
5. Raise front of vehicle and support securely on jack stands under the frame rails
6. Remove any skid plates or splash shields that may obstruct access to engine mounts

Procedure

1. 1

   Support the engine
   Position a floor jack with a wood block on the saddle beneath the oil pan. Raise jack until it just contacts the pan with minimal upward pressure. The wood block protects the pan from damage. Alternatively, install an engine support bar across the fender wells with chains attached to engine lift points.
2. 2

   Identify mount locations
   Locate both front engine mounts on the 390 V8. These are positioned on each side of the engine block, connecting the engine to the frame-mounted brackets. Each mount consists of a rubber isolator bonded between two metal plates with through-bolts.
3. 3

   Remove driver side mount upper fasteners
   Working from above, remove the bolts securing the top of the driver side engine mount to the engine block bracket. These typically use 9/16 inch or 5/8 inch fasteners. Support the fasteners as you remove them to prevent dropping into the engine bay.
4. 4

   Remove driver side mount lower fasteners
   From underneath the vehicle, remove the through-bolt and nut securing the driver side mount to the frame bracket. Note the orientation of any washers or spacers. The mount may remain stuck to the bracket due to age and corrosion.
5. 5

   Raise engine slightly on driver side
   Using the floor jack, carefully raise the engine approximately 1-2 inches to relieve pressure on the driver side mount. Monitor all engine-attached components (hoses, wiring, accessories) to ensure nothing is being strained or stretched. Do not raise excessively.
6. 6

   Extract driver side mount
   Remove the driver side engine mount from between the engine bracket and frame bracket. If stuck, use a pry bar carefully to break it free. Inspect the mounting surfaces on both brackets for damage, cracks, or excessive wear. Wire brush clean if installing new mount.
7. 7

   Install new driver side mount
   Position the new driver side engine mount between the engine and frame brackets. Ensure proper orientation with rubber isolator positioned correctly. Start all fasteners hand-tight before final tightening. Lower engine onto mount with jack to align holes if necessary.
8. 8

   Tighten driver side mount fasteners
   Tighten the upper engine bracket bolts first, then the lower through-bolt and nut. Typical torque specifications for these mounts are 35-45 ft-lbs for the upper bolts and 40-50 ft-lbs for the through-bolt, though verify with AMC service manual if available. Ensure mount is seated properly before final torque.
9. 9

   Remove passenger side mount upper fasteners
   Repeat the removal process for the passenger side mount. Remove the bolts securing the top of the mount to the engine block bracket. Access may be more restricted on this side due to accessory placement.
10. 10

    Remove passenger side mount lower fasteners and extract mount
    Remove the through-bolt and nut from underneath, then carefully raise the engine 1-2 inches on the passenger side using the floor jack. Extract the old mount and clean mounting surfaces. Check for frame bracket damage or elongated bolt holes.
11. 11

    Install and tighten passenger side mount
    Install the new passenger side engine mount in the same manner as the driver side. Position mount, start all fasteners hand-tight, lower engine to seat mount properly, then torque upper bolts to 35-45 ft-lbs and through-bolt to 40-50 ft-lbs or per manufacturer specification.
12. 12

    Lower engine and remove support
    Slowly and carefully lower the floor jack to allow the engine to settle onto both new mounts. Remove the jack and wood block from beneath the oil pan. If using an engine support bar, carefully release tension and remove equipment.

Reassembly

1. Reinstall any splash shields or skid plates removed during preparation
2. Reconnect negative battery cable
3. Lower vehicle from jack stands

Verification

• Start engine and observe for proper positioning - engine should sit level without excessive tilting
• Check for abnormal vibration at idle and under load - new mounts should significantly reduce vibration transferred to chassis
• Visually inspect both mounts with engine running to ensure no excessive movement or separation
• Test drive vehicle and verify smooth acceleration without engine movement or clunking noises
• After 50-100 miles, recheck all mount fasteners for proper torque as mounts may settle slightly

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