90K Service

Comprehensive 90,000 mile service for the 1970 AMC Rebel Machine 390ci V8 including fluid changes, filter replacements, ignition system service, and inspection of critical wear components.

Warnings

Tools required

Parts

• Engine oil filter × 1 — Use OEM specification for 390ci V8
• Air filter element × 1 — Use OEM specification
• Fuel filter × 1 — Inline or carburetor inlet type
• Spark plugs × 8 — Champion N-12Y or equivalent
• Distributor cap × 1 — Use OEM specification
• Distributor rotor × 1 — Use OEM specification
• Ignition points set × 1 — If equipped with points ignition
• Condenser × 1 — If equipped with points ignition
• PCV valve × 1 — Use OEM specification
• Differential gasket or RTV sealant × 1 — Use OEM specification
• Transmission pan gasket × 1 — Use OEM specification for automatic transmission

Fluids

• SAE 10W-40 or 10W-30 engine oil — 5 qt
• Automatic transmission fluid (Type A or Dexron) — 4 qt
• Differential gear oil (SAE 80W-90 or 85W-140) — 3 qt
• Engine coolant (50/50 mix) — 16 qt
• Brake fluid (DOT 3) — 1 qt
• Chassis grease (NLGI Grade 2) — 1 qt

Preparation

1. Park vehicle on level ground and engage parking brake
2. Place wheel chocks behind rear wheels
3. Allow engine and exhaust system to cool completely (minimum 2 hours)
4. Gather all necessary fluids, filters, and parts before beginning
5. Raise vehicle with floor jack and secure on jack stands at frame rails
6. Remove negative battery cable to prevent accidental shorts during electrical work

Procedure

1. 1

   Engine oil and filter change
   Position drain pan under engine oil pan. Remove drain plug and allow oil to drain completely (approximately 15 minutes). Remove oil filter using filter wrench. Clean filter mounting surface on engine block. Apply thin film of new oil to new filter gasket. Install new filter hand-tight plus 3/4 turn. Reinstall drain plug. Fill engine with 5 quarts of fresh oil through valve cover oil cap.
2. 2

   Cooling system drain and refill
   Ensure engine is cool. Place drain pan under radiator. Open radiator petcock at bottom of radiator or remove lower radiator hose. Drain coolant completely. Remove radiator cap. Flush system with water if coolant is contaminated. Close petcock or reinstall hose clamp. Fill radiator with 50/50 coolant mixture until full. Fill coolant recovery tank to cold mark. Start engine and run until thermostat opens, adding coolant as needed. Check for leaks.
3. 3

   Automatic transmission service
   Position drain pan under transmission pan. Remove all pan bolts except two at front corners, loosening these last to allow pan to tilt and drain. Remove pan and gasket. Clean pan and magnet thoroughly. Inspect for excessive debris or metal shavings. Replace transmission filter if accessible. Install new gasket and pan. Fill transmission through dipstick tube with approximately 4 quarts of Type A or Dexron fluid. Start engine, shift through all gears, and check level with engine running in Park.
4. 4

   Differential service
   Position drain pan under differential. Remove differential cover bolts and carefully pry cover loose. Allow gear oil to drain. Clean cover and housing mating surfaces thoroughly, removing all old gasket material. Inspect gear oil for metal particles or excessive wear debris. Install new gasket or apply RTV sealant to cover. Reinstall cover. Fill differential through fill plug hole until oil reaches bottom of fill hole threads (approximately 3 quarts). Install fill plug.
5. 5

   Air and fuel filter replacement
   Remove air cleaner wing nut and lid. Remove old air filter element and inspect housing for debris. Wipe housing clean. Install new air filter element. For fuel filter, locate inline filter between fuel pump and carburetor or at carburetor inlet. Use two wrenches to prevent twisting fuel line while removing filter. Note flow direction arrow on new filter. Install new filter with flow direction toward carburetor. Tighten fittings securely.
   ⚠Have rags ready to catch fuel spillage when removing fuel filter; work in well-ventilated area away from ignition sources
6. 6

   Spark plug replacement
   Number and remove spark plug wires one at a time to maintain firing order. Clean debris around each spark plug with compressed air before removal. Remove all 8 spark plugs using 5/8" spark plug socket. Inspect old plugs for fouling, wear, or incorrect heat range. Gap new spark plugs to 0.035" using gap tool. Apply anti-seize compound to plug threads. Install new plugs hand-tight, then tighten 1/4 turn with socket. Reinstall plug wires in correct firing order (1-8-4-3-6-5-7-2).
7. 7

   Distributor cap, rotor, and points service
   Mark distributor housing position relative to engine block with chalk or paint. Remove distributor cap hold-down clips or screws. Inspect cap for cracks, carbon tracks, or burned terminals. Remove rotor and inspect. If equipped with points ignition, remove points and condenser. Clean distributor cam with solvent. Install new condenser and points set. Adjust point gap to 0.016-0.019" using feeler gauge with rubbing block on distributor cam high point. Install new rotor and cap. Verify rotor does not contact cap terminals.
   ℹ️Points gap directly affects dwell angle and timing; verify setting carefully for optimal performance
8. 8

   Ignition timing adjustment
   Connect timing light to number 1 cylinder spark plug wire. Locate timing marks on harmonic balancer and timing tab. Start engine and warm to operating temperature. Disconnect and plug vacuum advance hose at distributor. Aim timing light at timing marks while engine idles. Initial timing should be set to manufacturer specification (typically 5° BTDC). Loosen distributor hold-down clamp. Rotate distributor body to adjust timing. Tighten hold-down clamp and recheck timing. Reconnect vacuum advance hose.
9. 9

   PCV valve and breather replacement
   Locate PCV valve in valve cover or intake manifold. Pull valve from grommet. Shake valve to verify it rattles (indicating it's functional). Install new PCV valve into grommet, ensuring tight fit. Check all crankcase breather hoses for cracks or deterioration. Replace as needed. Verify breather cap in opposite valve cover is clean and functional.
10. 10

    Chassis lubrication
    Using grease gun loaded with NLGI Grade 2 chassis grease, lubricate all grease fittings including: upper and lower ball joints (both sides), tie rod ends (both sides), idler arm, pitman arm, driveshaft U-joints (front and rear), and transmission linkage points. Pump grease until clean grease appears at seal or joint begins to swell slightly. Wipe excess grease from fittings.
11. 11

    Brake system inspection and fluid check
    Inspect brake master cylinder fluid level in both chambers. Add DOT 3 brake fluid if low. Remove all four wheels. Inspect brake pads or shoes for remaining material (minimum 1/8" lining). Check for fluid leaks at wheel cylinders and calipers. Inspect brake lines and hoses for cracks, bulges, or corrosion. Check brake drum or rotor condition. Measure brake pedal free play (should be 1/4" to 1/2"). Reinstall wheels.
12. 12

    Belt and hose inspection
    Inspect fan belt, alternator belt, and power steering belt (if equipped) for cracks, glazing, or fraying. Check belt tension by pressing midway between pulleys; deflection should be approximately 1/2". Adjust tension at component mounting bolts if needed. Inspect all radiator hoses, heater hoses, and vacuum hoses for soft spots, cracks, or deterioration. Squeeze hoses to check for internal deterioration. Replace any suspect hoses.
13. 13

    Suspension and steering inspection
    With vehicle on jack stands, grasp each front tire at top and bottom and check for play indicating worn ball joints. Grasp tire at front and rear and check for play indicating worn tie rod ends or wheel bearings. Inspect shock absorbers for fluid leaks. Check suspension bushings for deterioration. Inspect steering linkage for wear or damage. Lower vehicle and bounce each corner to test shock absorber function.
14. 14

    Carburetor adjustment and idle speed setting
    With engine at full operating temperature, connect tachometer. Ensure choke is fully open. Adjust idle speed screw to achieve manufacturer specified idle speed (typically 600-650 RPM in Drive for automatic, 700 RPM in Neutral for manual). Turn idle mixture screws out equally until engine runs rough, then turn in until engine smooths out, then turn out 1/4 turn for optimal mixture. Readjust idle speed if necessary. Verify smooth acceleration without stumbling.
15. 15

    Final fluid level verification and test drive
    Recheck all fluid levels with engine warm: engine oil (dipstick), transmission (dipstick with engine running in Park), coolant (radiator and recovery tank), brake fluid (master cylinder), and differential (fill plug check). Lower vehicle from jack stands. Reconnect battery negative cable. Start engine and verify no warning lights. Check for any fluid leaks under vehicle. Perform test drive to verify proper operation of all systems. Monitor engine temperature gauge for normal operating range.

Reassembly

1. Ensure all drain plugs and fill plugs are properly installed and tightened
2. Verify all filter housings and covers are securely fastened
3. Confirm all spark plug wires are routed correctly and seated fully
4. Double-check that distributor cap is properly clipped or screwed down
5. Ensure battery negative cable is reconnected securely
6. Confirm wheels are torqued to specification and lug nuts properly tightened

Verification

• Start engine and verify smooth idle with no unusual noises or vibrations
• Check for fluid leaks under vehicle after engine reaches operating temperature
• Verify all gauges read normal (oil pressure, temperature, charging system)
• Test drive vehicle and confirm smooth acceleration, proper shifting, and adequate power
• Verify engine temperature remains in normal range during and after test drive
• Recheck all fluid levels after test drive and top off as necessary
• Confirm no warning lights are illuminated on instrument panel
• Document service completion and reset service interval reminder if equipped

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