This procedure covers removal and replacement of the timing chain, sprockets, and related components on a 1966 Chevrolet Corvette 327ci V8, including proper alignment and tensioning.

Warnings

Tools required

Parts

• Timing chain kit (chain, cam sprocket, crank sprocket) × 1 — Use OEM specification or Cloyes 9-3100
• Timing cover gasket × 1 — Use OEM specification
• Timing chain tensioner (if equipped) × 1 — Use OEM specification
• Harmonic balancer seal × 1 — Use OEM specification
• Oil pan gasket (if disturbed) × 1 — Use OEM specification
• Water pump gasket (if disturbed) × 1 — Use OEM specification
• RTV silicone sealant (Permatex Ultra Grey) × 1 — Permatex 82194

Fluids

• 5W-30 Conventional Engine Oil — 5 qt
• DEX-COOL Extended Life Coolant (Orange) — 10 qt

Preparation

1. Disconnect negative battery cable
2. Drain engine coolant completely into suitable container
3. Drain engine oil and remove oil filter
4. Remove radiator upper and lower hoses
5. Remove radiator (provides better access to timing cover)
6. Remove fan shroud if equipped
7. Remove engine fan and water pump pulley
8. Remove drive belts (alternator, power steering, air conditioning if equipped)
9. Remove distributor cap and mark rotor position relative to block
10. Position vehicle on level surface with parking brake engaged

Procedure

1. 1

   Remove harmonic balancer
   Using a breaker bar and appropriate socket, remove the crankshaft pulley bolt (center bolt on harmonic balancer). Install harmonic balancer puller and evenly tighten the puller center bolt to remove the balancer from the crankshaft. Note the orientation of the balancer keyway for reinstallation.
2. 2

   Remove water pump
   Remove the 6 water pump mounting bolts and carefully pull the water pump away from the timing cover. The pump may be sealed with gasket material or RTV. Set aside with gasket for inspection.
3. 3

   Remove timing cover
   Remove all timing cover bolts (there are 8 bolts around the perimeter of the cover). The timing cover may have 2 bolts at the top, 3 bolts on each side, and bolts at the bottom that thread into the oil pan. Carefully pry the timing cover away from the block using a flat pry bar at the designated pry points. Do not damage the sealing surfaces.
4. 4

   Verify timing mark alignment
   Before disturbing the chain, rotate the crankshaft using a socket on the crankshaft bolt until the timing marks on the camshaft sprocket and crankshaft sprocket are aligned and facing each other. The marks should be closest together at the 6 o'clock position relative to the camshaft sprocket. Take a photograph for reference.
5. 5

   Remove camshaft sprocket and chain
   Remove the 3 camshaft sprocket bolts. Use a holding tool or have an assistant hold the camshaft from rotating if necessary. With bolts removed, pull the camshaft sprocket and timing chain forward together off the camshaft. The chain should slide off both sprockets as a unit. If sprocket is tight on camshaft, use light taps with a soft mallet on the sprocket face while pulling outward.
6. 6

   Remove crankshaft sprocket
   Remove the crankshaft sprocket by pulling it straight off the crankshaft snout. If tight, use two pry bars positioned opposite each other behind the sprocket, or use a gear puller. Note the orientation of any locating key or keyway.
7. 7

   Inspect timing chain components
   Inspect the old timing chain for excessive stretch by measuring 12 links and comparing to new chain (should not exceed 0.125 inch elongation). Check both sprockets for worn or hooked teeth. Inspect the timing chain guide or tensioner (if equipped) for wear grooves. Replace any worn components.
8. 8

   Clean all sealing surfaces
   Thoroughly clean the engine block timing cover surface, oil pan mating surface at the timing cover, and the back of the timing cover itself. Remove all old gasket material and RTV using a gasket scraper. Clean surfaces with brake cleaner and wipe dry. Inspect for damage or warping.
9. 9

   Install crankshaft sprocket
   Install the new crankshaft sprocket onto the crankshaft with the timing mark facing outward. Align the keyway with the crankshaft key. Tap the sprocket onto the crankshaft using a soft mallet or press it on using the crankshaft bolt and a thick washer. Ensure the sprocket is fully seated against the crankshaft shoulder.
10. 10

    Install timing chain and camshaft sprocket
    Loop the new timing chain over the crankshaft sprocket with the timing mark at the 12 o'clock position. Position the camshaft sprocket into the chain with its timing mark at the 6 o'clock position so both marks face each other. Install the camshaft sprocket onto the camshaft dowel pin, ensuring the dowel pin engages the sprocket properly. Verify both timing marks are aligned and closest together before proceeding.
    Torque spec

    Camshaft Sprocket Bolts80 Nm (59 lb-ft)
11. 11

    Install camshaft sprocket bolts
    Install the 3 camshaft sprocket bolts finger-tight. Verify timing marks remain aligned. Torque the camshaft sprocket bolts to 80.0 Nm (59.0 lb-ft) in a crossing pattern to ensure even seating. Double-check timing mark alignment after torquing.
    Torque spec

    Camshaft Sprocket Bolts80 Nm (59 lb-ft)
12. 12

    Install timing chain tensioner or guide
    If your engine is equipped with a timing chain tensioner or guide, install it now. Position the tensioner/guide and install the mounting bolts. Torque the timing chain guide bolts to 12.0 Nm (9.0 lb-ft). If a tensioner is present, torque to 25.0 Nm (18.0 lb-ft) per specification.
    Torque spec

    Timing Chain Guide Bolts12 Nm (9 lb-ft)

    Timing Chain Tensioner25 Nm (18 lb-ft)
13. 13

    Verify timing chain installation
    Manually rotate the crankshaft two complete revolutions clockwise (viewed from front) using a socket on the crankshaft bolt. The timing marks should align again at the same position. If marks do not align, the chain is installed incorrectly and must be removed and reinstalled. Check for proper chain tension and smooth operation through the entire rotation.
14. 14

    Prepare timing cover for installation
    Install the new harmonic balancer seal into the timing cover, driving it in evenly with a seal driver or appropriately sized socket. Apply a continuous 3mm bead of RTV silicone to the block timing cover surface, circling all bolt holes. Apply RTV at the oil pan-to-block junction where the timing cover meets (front corners). Position the new timing cover gasket if using a gasket instead of RTV only.
15. 15

    Install timing cover
    Carefully position the timing cover onto the engine block, ensuring it seats properly over the crankshaft snout and aligns with all bolt holes. Install all 8 timing cover bolts finger-tight first to ensure proper alignment. Torque all timing cover bolts to 12.0 Nm (9.0 lb-ft) in a cross-pattern starting from the center and working outward. Do not overtighten as this may distort the cover.
    Torque spec

    Timing Cover Bolts12 Nm (9 lb-ft)
16. 16

    Install water pump
    Install a new water pump gasket or apply RTV to the water pump mounting surface per gasket instructions. Position the water pump onto the timing cover and install the 6 water pump bolts. Torque bolts evenly in a crossing pattern to manufacturer specification (typically 30 lb-ft for small block Chevy).
17. 17

    Install harmonic balancer
    Ensure the crankshaft keyway and harmonic balancer keyway are clean and undamaged. Apply a thin coat of engine oil to the crankshaft snout and inner surface of the balancer seal. Slide the harmonic balancer onto the crankshaft, aligning the keyway. Install the crankshaft bolt with washer and torque to 180.0 Nm (133.0 lb-ft), then rotate an additional 90 degrees. Verify the balancer is fully seated against the timing cover.
    Torque spec

    Crankshaft Sprocket Bolt180 Nm (133 lb-ft) + 90°
18. 18

    Reinstall accessories
    Reinstall the water pump pulley, engine fan (note direction of fan blades), fan shroud if equipped, and all drive belts. Adjust belt tension to specification (typically 0.5 inch deflection at longest span). Reinstall alternator, power steering pump, and air conditioning compressor brackets as needed.
19. 19

    Reinstall radiator and coolant system
    Reinstall the radiator and secure with mounting bolts. Reconnect upper and lower radiator hoses with new clamps if originals are worn. Reconnect heater hoses. Fill cooling system with 10 quarts of DEX-COOL Extended Life coolant mixed 50/50 with distilled water.
20. 20

    Refill engine oil and final checks
    Install a new oil filter and refill engine with 5 quarts of 5W-30 conventional engine oil. Reconnect the negative battery cable. Verify distributor rotor is in the original marked position. Double-check all bolts, hoses, and electrical connections are secure.

Reassembly

1. Ensure all timing marks were properly aligned before rotating engine
2. Verify harmonic balancer is fully seated and not cocked on crankshaft
3. Check that all accessory belts are properly tensioned
4. Confirm all coolant hoses are secured with clamps
5. Verify oil level is correct on dipstick after filling

Verification

• Start engine and immediately check for oil pressure on gauge (should register within 5 seconds)
• Listen for any abnormal noises from timing chain area during startup and idle
• Check for coolant or oil leaks around timing cover, water pump, and oil pan
• Allow engine to reach operating temperature and verify proper thermostat operation
• Check ignition timing with timing light and adjust distributor if necessary to factory specification (typically 4-8 degrees BTDC at idle)
• After initial 20 minutes of operation, shut down engine, allow to cool, and recheck coolant level
• Recheck all timing cover bolts and water pump bolts for proper torque after first heat cycle

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